Renix TPS Adjustment


Before attempting to adjust your TPS, there are a few things that need to be done.

  1.  Be sure the throttle body has been recently cleaned. It’s especially important that the edges of the throttle butterfly are free of any carbon build-up.
  2.  With the KEY OFF, and using the positive (red) lead of your ohmmeter, set on the lowest scale, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself.
  3. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall.

If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. It is covered in detail in Tip 6.


Both Renix manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire “A” is positive. Wire “B” is ground. DO NOT UNPLUG THE CONNECTORS!Backprobe 2

  1. KEY ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage.
  2. KEY ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage.
  3. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts.
  4. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage.
  5. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can’t achieve the correct output voltage, replace the TPS and start over.

Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.


Renix automatic transmission-equipped XJs and MJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY.


  1. KEY ON, measure voltage between “A” positive and “D” ground by back-probing the connector. Note the voltage. This is your REFERENCE voltage.
  2. Back-probe the connector at wires “B” and “D”. Measure the voltage. This is your OUTPUT voltage.
  3. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts.
  4. Adjust the TPS until you have achieved this percentage. If you can’t, replace the TPS and start over.

So, if you have an automatic equipped XJ your TPS has two sides–one side feeds the ECU, and the other side feeds the TCU.

For those with a MANUAL TRANSMISSION–the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced. The square 4 wire connector is just not used.

Revised 7/08/17

212 thoughts on “Renix TPS Adjustment”

      1. I have no voltage when trying to get a voltage reference reading. The key is in the on position. The jeep has a long crank but when started it runs fine. Is that possible with no voltage reference?

  1. If you move the tps for the transmission adjustment won’t it change your adjustment for the engine side of the tps?

    1. Yes it will. Thanks for bringing this up.

      BUT, the Transmission side of the TPS is no where near as critical as far as adjustment as the Engine side is.
      The rule of thumb here is you use the Trans side to DIAGNOSE issues with that side of the TPS, but always ADJUST the TPS using the Engine side.

  2. I spoke to soon. I don’t know we’re I posted it but, I thought I had fixed my jeep idle issues with switching in a different tps . That didn’t work after a short drive down the rd. I checked the voltage and couldn’t get a reading on the 17% side or b and c reading so I figured the other used tps was bad too. I then went and bought a new tps. All the voltage readings came out perfect and it did good til the motor warmed up. Jeep still won’t idle. I am really burnt out at this point. Kind of don’t know what to try next. Is there another place to adjust the idle on this thing? It’s got to be something simple cause this things runs like a top off of idle.

  3. I was checking back over everything I had touched mentally today and realized during throttle body cleaning and IAC cleaning that I may have moved something. The kick down cable crossed my mind and I had no idea it did anything with idle. However, I adjusted it while the jeep was idling and now the jeep runs like a top! Guess I moved the cable setting when I unhooked it during cleaning. I am surprised no one else seems to have run into this. Hopefully all my heart ache can help someone else. Didn’t need any new parts just brain power.

  4. Is the setting and adjustment the same for both renix engines:
    2.5L4 TBI and 4.0L6
    each with manual transmission?
    17% of incoming voltage = outcomig voltage?

  5. Hi Cruiser54, Thanks for putting this site up and answering questions.
    I have an ’87 XJ Limited Wagoneer with 4.0 and AW4. It has been well taken care of but some of the maintenance has been worked around, such as a momentary switch under the dash to bypass the neutral start switch. 🙂 We have driven it only some 5k miles, now showing 130k. It has always seemed anemic and we were discussing possibilities and the primary driver said it seems the pedal just doesn’t go down far enough. As for the TPS the reference is 5.2V, closed .9V, pedal floored 3V and WOT at the throttle body 4.4V. Electrical questions: At WOT should the output equal the reference?

    On the physical side the pedal does not completely open the throttle plate (lacks about 1/3) before before the arms hits the floor. There is a depression in the carpet so that is likely the problem. Do you remember if perchance there was extra padding or something under the carpet that would restrict the pedal movement?

    Thanks again,


    1. Not uncommon Dean. The carpet got in the way. Do what you can to get around that. I’ve actually lifted up on the pedal rather strongly to gain the travel back.
      When is the last time it got plugs, wires, cap , rotor and throttle body cleaned?
      Since it is an 87, I would strongly suggest doing Tips 1,3, 4, 5, and 27. Make sure the intake manifold bolts are tight.
      The vacuum line from the throttle body to MAP sensor has to be perfect also.
      If you haven’t indexed your distributor per Tip 13, that would be a good start.

      1. Cruiser54, methinks thou hath been miss dubbed. If you can bend that throttle rod by hand I really think Bruiser98 would be more applicable. 🙂
        I got but I put a block between the firewall and rod on the top to protect another gizmo than used a hydraulic spreader under the pedal end and it finally acquiesced.

        I would like to eliminate the C101 and index the distributor but that is another day. This is a ’87 Wag and the sight tube for setting the timing opens right onto the back side of the serpentine belt. Does that mean the only way of finding TDC is the “old fashioned” way?

  6. Hey I have a problem with my 1990 renix that I can’t put my finger on. I’m wondering if you can shed some light on the situation. I keep getting a high idle once everything is warmed up and sputtering between 1500 and 2000 rpm. The sputtering is intermittent and occasionally backfires when it is happening. The high idle is almost all the time. Anything you can think of would be awesome before I start ripping everything apart and replacing everything lol. I don’t have a lot of time to start diagnosis on everything in your guide due to work and kid’s so if you could give me your best guess on where to start that would be great! This is my first renix and I have never run into this problem with any of my other jeeps.

  7. First – thanks for these excellent articles. They’ve already been a huge help getting my Jeep back on the road.

    I’m did these tests as part of figuring out a low power condition, and all signs are pointing to the transmission side of the TPS being the issue. I tested the engine plug and made a small adjustment to bring it into range. However the transmission side seems to have zero reading. No power at either terminal and the ground seems bad as well.

    Any tips on sorting this out? I’ve already done some ground upgrades while following your ground refresh article and they seemed to help.

    1. Glad the Tips are helping you.
      The dipstick tube stud ground is a huge player in this. See Tip 1.

      Tip 10 should also be done as well as the Connector Refreshing.

      See what you get for readings at the TPS Trans connector after that.

      Have you done Tip 5?

      1. Hi cruiser, like every one else here (except that one guy) I am so glad to have found your treasure trove of information and your ready responses. Of course, I hope you are still “on the air”.
        To the point, I have the same problem as this gent (Kap) in that I have 0 values at the tranny side of the TPS. This is a 1987 4.0 auto that I got as a beater and am slowly resurrecting from 312K miles of less than gentle care. The transmission shifted fine until a few months ago when I changed the fluid and screen in the tranny (Dex/Merc V, I think). At about the same time the tranny quit shifting and I first thought the TV cable had lost it’s bottom end (adjustment at the throttle body didn’t seem to do much. Drained and took off the tranny pan and the cable was fine, likewise the cable to the solenoids were all intact (didn’t check them electrically). Refilled it and have been shifting manually ever since. Oh, one time I left it in drive and after about 20 min. it started shifting again, but after that time it never has again. Anyway, that was about the time i found your website and have been doing the Tips as I could get to it. Did Tip 1 and thought that would do it (could they make it any harder to get to?), but no real change. Today i got to the ground refresh and the bundle of brown w/ white connecting to the single had at least 4 b/w’s to the one. The one closer to the C101 had just three to one. It’s not clear which single wire you are referring to to delete, so I just clipped the copper crimp and soldered the wires back as I found them with heat shrink. Te bundle near the engine already was soldered but with the Duct tape off there was no protection. I clipped the single wire and stripped and soldered it to the bundle and heat shrunk it. These two single wires seem to go to separate places and that is where I got confused.
        So now i have gone from 15ohms to .5 without any change due to wiggling (on the TPS plug) Output value was slightly high and I adjusted it, then the idle was kind of high and used the technique you mentioned and it worked. Ok, all is rosy, so I check the tranny plug and no voltage D>A or D> B. I’m wondering where the voltage is supposed to be coming from and check the two fuses again (both fine) then he voltage at the one by the TCU – 11.85v across the contacts with the fuse out. Then the brainstorm happened and I checked the ohms from “D” to the battery. Infinity. So the voltage to A and B using the battery as ground was right on spec. Now I have to find the breakdown between the D and ground.
        I don’t know if Kap ever found his problem but thought that might help. Apparently when I changed the filter I knocked some ground loose or at least out of sorts, but when I did tip 1 I didn’t find any loose wires.
        Just as a reminder that nothing is too basic, I checked the ohms between battery ground and the dipstick stud and got 10ohms! This was after I did Tip 1 last week but didn’t check this afterward. Turns out the battery terminals are the kind where there are two bolts and a plate holding the cables in and they appeared tight but when tugged one came out! Did a refresh on THAT connection and my 10ohms dropped to .5.

        1. The TPS, on the “trans side”, should have 5 volts DC at the gray wire on the TPS.
          This voltage originates at the TCU terminal D1.
          It then goes through the C101 to the TPS plug. Gray wire.

  8. My ’88 XJ has been idling @ roughly 1200-1500 for a while now. Decided to check TPS hoping that would remedy this.

    I did the ground / 101 / engine bay connector refreshing bit shortly after buying the rig roughly two years ago.

    TPS reference * .17 gives a target voltage of .81v. Found it @ .3v or so. I’m thinking at this point “Voila! I’ve found my problem.”

    Maybe, but after adjusting the TPS my idle jumps to 3500. This being a little high(!) I followed the “high idle after adjusting” tip.

    Long story short, if I set the TPS to any voltage over .4 or so, I get a 3500 rpm idle.

    Bad TPS? Something else I’m missing (a not-unlikely possibility)?

    I don’t wanna start shot-gunning this problem with my wallet (parts-cannon).

    Thanks in advance. (go ahead, I’m prepared to be embarrassed)

      1. Yeah I did, and re-checked the TPS ground before attempting the adjustment. The rest of the grounds were cleaned two years ago, but I was new to the Renix world then… I’ll go back & re-check/clean ’em.

        Reading through the list of tips, I’m going to check a couple other items off the list as well (as time & weather allow). It’s been running rich for a while also, so going to check out the Coolant temp sensor, MAT & MAP before I try the TPS again.

  9. I’m having a slight high idle as well, around 1,000 – 1,200ish when warmed up. I have tried setting the TPS to 17% output putting it at about .827 volts and it still idles high. Then I decided to set it lower (.700 volts) and it idles about 700ish until the throttle is pushed, and back up it goes. If I unplug the TPS while it’s running and “blip” the throttle, the idle comes back down to normal, but will go back up once the TPS is plugged back in and throttle is pushed. This is a fresh 4.7 stroker that runs strong, but doesn’t like to idle normal.

  10. The throttle body was cleaned recently, including the IAC. The throttle stop is set for the smallest movement of the butterfly from touching. I bought another new TPS, added two #4 ground wires (from intake manifold to firewall, and dipstick bracket to a stud below the coil), plus a new battery ground cable to the dipstick bracket. I also soldered a new connector to the group of small wires that go to the dipstick bracket. When checking ohms from ground on the flat TPS connection to the battery, I get almost a perfect zero. I’ve sprayed throttle body cleaner all around with the engine running and didn’t notice any idle change. I even set the TPS down to .500 volts and it still wants to creep up to 1,000 – 1,200.

    I’m at a loss here, but will try whatever is next, possibly a fire, then to the crusher?

  11. My Jee: 89 4.0L auto. I have had the high idle issue for about 2 years now. I refreshed the grounds at the dip stick and the firewall and added 8gauge wires to the ground. I’m on my 3rd AIS motor and 3rd TPS, I put new 4 relays behind the battery, I cleaned all the plug connectors and added diletric silicone at the junctions. My issue is most times the engine would start normal and the idle would go up about 5 minutes on. I shut it and restart, sometimes it would go back to normal and idle at 600 rpm and every once in a while it would race to 3000 rpm. Today I was checking the Ohm reading from the flat switch B terminal and I got 3.7 ohms. How do I remedy this issue.


    1. Have you performed Tip 5? I’m guessing that’s what you are referring to.

      If so, Tip 6 outlines the repair of that ground circuit common to numerous sensors.

  12. Thanks, I did tip 5 and the result I got is 3.7 ohms on the B terminal instead of 1 or less. Does tip 6 cover the procedure on how to remedy the ground issue or there is more you can with.


    1. Hats off to Cruiser. After a couple.of years of dealing with erratic high RPM issues, I finally got the time to get the time to work on the wiring harness. I cut and soldered the grounds. So far, I have had no more issues with the engine racing.
      A million thanks, you saved the Jeep!
      I had almost given up. All the items I replaced multiple times were not the cause.
      Thanks again

  13. Hi cruiser54 this website is awesome lots and lots of helpful tips. I have 1990 renix 4.0 replaced every senor in it yea I know but thats how I am lol. Anyway my problem is once is warm driving normal when I let off the accelerator it wants to die then it will catch up and running fine I have tested and checked everything three times or more I’m out of ideas and in need of some help

  14. I have a 1990 with the 2.5L/manual trans….your advice that the automatic transmission TPS will work is incorrect! I bought one and its a very different setup. If I’m wrong…let me know.
    I’ve wasted $12.00 on your word and don’t want to waste any more.


    1. I must have misunderstood you then, because I know the 2.5 auto and manual TPSs don’t interchange, but the 4.0s do.

      The website is supposed to notify me as soon as a comment is made. didn’t do it til today.

  15. You have not posted my email about the TPS false claim. I see that you
    are vain and cannot take criticism.

    Please be MAN enough to get rid of the false claim that the auto
    TPS will fit the 2.5L manual transmission.


    1. You know Dean, I operate this website, pay for it myself, selflessly try to help folks without any payment.
      Your comment makes me wanna puke.

      I have done my best to answer all of your questions in a timely and accurate manner. MANY questions.
      Oops, I misunderstood something and cost you a measly $12? boo-hoo.

      So you attack me personally?
      Don’t expect any more help from me.

  16. hey cruiser, I appreciate all the info (and to hell with the last guy who gave you crap) and this helped me diagnose my bad TPS today. It is .85v at idle and then as soon as it comes off it drops to almost 0 until about 15% throttle where it performs as it is supposed to, which explains the hard stumble off idle, and hopefully the other running issues, but we’ll see after I run to the parts store. One question I have for you though is why my TPS has 6 wires and both plugs when it is, and has always been, a five speed. The auto transmission plug IS plugged in, and that set of wires dives into the harness and heads towards the firewall and the C101 (which I eliminated as per your instructions.) Any ideas on this? I am the second owner and it most definitely has been a manual its whole life and there is no sign of harness butchery. I am on my way to the parts store to get a new one, and am unsure about whether to get the manual or auto TPS now, since those wires go somewhere… I wonder if there is another input to the computer? or maybe it was just the general harness and those wires terminate in a connector. Either way I figured I would see if you had seen this or had any thoughts? Thanks for everything you do, most of us appreciate it very much.

    1. Sorry for the slow response. The site is supposed to notify me immediately when questions are asked. Kinda spotty.
      Get the auto one. It’s waaaay cheaper.

      Don’t plug the trans side connector to your harness.

      Have you performed Tip 5 and cleaned your throttle body?

  17. My 1989 4.0 Auto 4×4 recently stopped shifting through the gears when placed in drive, but will perform fine when the shifter is moved manually. I was told this may be a TPS issue. Is this possible?
    I did the steps 1-4 & the headlight relay a year or so ago.

  18. Thanks for your contribution the renix owners. I’m not sure where the TPS adjustment is made at. Is it Full Throttle, close throttle our idle partial throttle.. I read through this a few times I can’t seem to find what position throttle play needs to sit. When making this adjustment.Thanks again.

  19. Man stumbling across this website was an absolute awesome mistake!! Before I even get started I have to say thanks for all the time and effort that has went into allowing the rest of us to learn from your knowledge.

    Now that’s out of the way lol, here is my situation.
    This past week I ran across an 89 Comanche 2wd with the 4.0 and auto transmission. The old man had all of the paperwork from were his father in law had bought it brand new. He said after the original owner passed, it sat up for 4-5 years before he acquired it and started to drive it. In the past 3-4 years they have barely put 2,000 miles on it. I drove it around and decided it would be a good truck for my wife to use for fishing or hauling off garbage while I am working on the road away from home. When I got home I found this site and realized there was hope and possible fully restoring this truck to normal working order rather than it just being something to beat around in.

    Issues that I have found so far-
    Will not shift own its on in auto. If I drop it down in 1-2 and just manually shift from there, it shifts and drives very smooth. BUT once I got it home I read here and started checking the 7.5 fuse under the steering wheel on the fuse panel along with the TCU and its 10 amp fuse. Both were good so I reinstalled them. (This was while it was running) then my kids want to go for a ride and I load them up. A few miles down some back roads I have it in drive (3rd gear I call it when manually shifting) and noticed it down shifted on its own when I slowed down. I stopped completely and took off and to my surprise it was shifting beautifully. It worked flawlessly for about 30 min or so with a lot of stop/go along with some heavy acceleration to make it down shift into a passing gear. Once home I killed the engine and the next time
    I cranked it up, its back to manually shifting because auto will not work at all again. I’m at an absolute loss to why it would randomly work that one time until the key was turned off so now I need advice on where I should be starting to fix this thing to shift normally.

    Also I have noticed that the radio, windshield wipers, interior lights, or any of the dash lights all Do not work at all. All fuses in the panel are in glod shape but I haven’t had time to check for power at the fuse panel.

    Another thing is when it is first cranked it idles great, until you try and take off. Sometimes it wants to bog down and die as soon as you touch the gas pedal. It seems like either it’s flooding itself or being deprived of fuel or air like when chocking a running small engine that is already running.

    Something else that I’m also not sure about it’s the spark plug wires. If it’s running and you touch one of the wires, is it supposed to shock you? Lol if not, I’ll change the plugs and wires.

    Sorry for the lengthy comment, just wanted to explain a little. Any help would be greatly appreciated

    1. Wow I started falling asleep when I wrote that last night and just realized I botched some words up pretty bad lol. If you need clearification on anything just let me know

      1. You’re good to go. Tips 1,3,4, and 5 first. New tune up parts as I posted earlier. NGK plugs are my favorite. ZFR5N.

        Check the intake manifold bolts and make sure none are loose.

    2. Do Tip 10. Put new plugs, wires, cap and rotor in it.

      Also, Tip 1 shows all the things that ground on the engine dipstick tube stud. The Transmission Control Unit is one of them.

  20. Hey bud, im having an issue adjustung the tps and i was wondering if you could help me out. I get 4.86 reference voltage and can only adjust the output voltage to .47 max. I’ve tried 3 different tps sensors including one from a friends truck that runs perfect, and they all read the same thing 4.86 ref. voltage and .47 output voltage. Another issue i’m having is the transmission shifts at the same speed and rpm regardless of throttle input with i believe is the fault of the tps as well. I’ve done most of the tips on here before i ever had this problem and have troubleshoot it for about a week now and just cant figure it out. Any help is appreciated

  21. Hey Cruiser – Thanks for your help via the forums and all the information here. I’m adjusting my TPS, but I can’t rotate it far enough when bolted in to register a voltage change. I need to press the arm on the back further than I can rotate it to hit my desired voltage. Is this a clear sign I need a new TPS? Can I adjust the screw in the back that holds the arm in?

    1. Aside from a bad TPS, check and see if the TPS is moving with the throttle body linkage. Make sure the tanggg for the TPS is on the correct side of the linkage.

  22. It was the thingy in back. Wasn’t positioned on the right side of the linkage. Perfectly set at 0.83. Not sure if that was me or the mechanic who just worked on it. I am working through Tips 1,3-5 and will update in the forum. Thinking of typing all the tips into a check-list format for myself. I’ll give it to you when I’m done if you want it.

  23. Hi Cruiser, I just recently purchased a 88 with the, 4.0 the previous owner had replaced the TPS but there were still issues with it idling high, you could get the idle to drop down by tapping on the tps so I purchased a good TPS from Napa, and then read your tips about getting rid of the factory crimps, so I did that along with cleaning all the grounds as well as replacing the ground to the firewall, all was good I got the tps adjusted and everything was fine, I have drove it around with no issues, then all of a sudden it started idling high again yesterday, and it will fix itself if I tap on the TPS, I can actually see the lever move when I do, not sure where to turn next… also I removed and cleaned the throttle body and redid the connector to the Map sensor. Thanks for all the information you have written up.


        1. Hi Cruiser, just now getting back I had ordered injectors and had issues with several leaking, finally got it straightened out, I also readjusted the tps as you suggested and so far it seems to have taken care of it idling high, but it still fluctuates up and down between 500 rpms and 700 I notice that if I wiggle the throttle plate linkage it changes, I’m thinking maybe the throttle body may be worn, is there someplace that rebuilds them or is a aftermarket one available? I didn’t really find anything that I knew would work, thanks again. Mel

  24. Let’s try and pinpoint the suspected vacuum leak.
    At idle, spray carb cleaner around suspected area. You’ll know when you find it. Used throttle bodies are available. It’s also rare that the throttle shafts leak.

    1. Ok I tried that and no change, I sprayed around the throttle body and all the vacuum lines, now its sitting here purring like a kitten lol, and now it’s not changing when I wiggle the throttle plate I seem to notice the idling change when I’m driving, I never no how it’s going to idle from one traffic light to another, but it never dies. I did notice it’s in dire need of motor mounts though… thanks again for your help. Its definitely come along way since I started with it.

  25. Hey cruiser I’ve tried adjust tps my resistance is 1 ohm and no matter how I set it either .83 .43 or .93 it’s all the the same it races up the only way it won’t is when I turn it as low as it will go idk if that is zero or not but right now it’s working whys that and all my grounds are good and clean

    1. Sounds like you’re using the specs for the trans side of the connector.


      Both Renix manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire “A” is positive. Wire “B” is ground. DO NOT UNPLUG THE CONNECTORS!Backprobe 2

      KEY ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage.
      KEY ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage.
      Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts.
      Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage.
      Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can’t achieve the correct output voltage, replace the TPS and start over.
      Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.

      1. I have tried this many times and sometimes I get a .48 output voltage on my TPS, sometimes I get zero. On my 3rd TPS and 2nd meter and 2nd set of probes. I can’t seem to get a good reading. I have done steps 1-7, 9-11, 31 and 36 so far. I am also on my 3rd CPS because none gets more that .35v.
        My only issue is the occasional random shut off and lack of power. Otherwise it’s doing great thanks to this site.
        I guess I will order another CPS, TPS and another meter and better probes.

        1. So, you’ve cleaned the C101 but not soldered the wires?

          You can bypass the C101 with just the CPS wires to eliminate that resistance.

          Odd output voltages from the TPS usually mean the TPS is bad.

  26. Hi cruiser i have done all your tps and im still having a problem with the transmisson shifting at wrong times. It got better when i replaced the tps and i put a tcu from a junk jeep in and it still has problems. Could the tcu be bad if im getting voltage when i prob the 4 prong with the key in the off position?

  27. Can I just loosen the screws on the tps and turn it while vehice is running(which way?) to lower the park idle? If not why not, I’m just cutting out the meter step? It use to idle at about 750rpm (good)now its at 1000.(bad) I’m a Wisconsinite and my concern is the colder it gets outside the higher that start-park idle is going to go. 1990 cherokee 4.0 automatic

    1. Thanks for the info.I think I’m going to try it that way. I cleaned the throttle body and replaced the iac and it did go back down for awhile then it went back up.(computer reset?) Maybe thats just where it likes to run with new iac,anyway thanks again and have a good labor day.

  28. This is what i have when i tested. My 90 just seems to want to die once in while like it is rich, but yet passed emissions. Starts fine, idles fine.
    A-B=.4.87 volts
    B-C= .43
    .41x.17= .069
    What am i suppose to be reading,
    What number is it suppose to be at to determine if defective.
    Also, i could not get a voltage reading from A-B until i turned the motor on and it was running.Will try again.
    So in my instance, my output should match the input,so my reading of .069 compared to .43 means my tps is bad.

  29. yes, i got a reading with just the key on. so a reading of .069 is not close to .82, so my tps is bad then, sometimes it just seems to run rich and wants to die like it is rich when just at idle or slowly moving less then 5mph. I went out to start it this morning and then wouldnt start. had to unplug the cps, turn over unplugged, then plug back in and it started right up.

    I passed en\missions 2 months ago flying colors, no problems though.

  30. Cruiser, thanks for the “book” this helped a lot, just cleaned the throttle body, checked the grounds, refreshened most of the connections and set the TPS, along with a set of rebuilt 4 hole injector my 90 XJ is running better than it has the 7 years I have owned it. Head light harness goes in tomorrow. Thanks, Bruce

  31. I have an 87 Cherokee auto I6. I’m having issue where it will shift rather quickly through gears and I’m in OD at like 30-35 mph unless I manual change gears. It will not down shift until i stop, even at full throttle. I tried adjusting the TV/kickdown cable and it won’t adjust with pedal or moving the TB linkage, maybe one small 1/16 click. I tested with volt meter on 3 wire TPS and was was getting 4.92 on A and B and only .22 MAX on the B and C. I couldn’t get anymore out of it. I’m confused as to where to go now. These do not have TCU until 88 from what I read? I don’t know I’m new to this, I’m used to working with 240sx.

  32. Ok, I greatly appreciate that. I’m going to work on that next. My question is if the TV/kickdown cable is bad since I can’t get any adjustment out of it. Where can I get another, are there any newer models that have same length specs, I looked everywhere and can’t find any specs on the cables and even Mopar vintage parts are discontinued and out of stock. No one seems to have them. I’m working on the throttle stop screw it’s bound up with still like 1/16-1/32″ gap between them so that needs adjusted as well.

  33. I will do that, although with the button pressed I can easily move it in and out it’s just when I press the button and slide it in when I use accelerator pedal OR twist throttle by hand I only get like 1/32-1/16″ oh a click out of it and that is it. I can’t imagine that is correct from all of the videos I have seen it comes out a good distance. Which was leading me to believe the cable adjuster may be stripped out of something along those lines. That’s why I have been looking for a new cable or a compatible cable, because when I do my transfer flush and filter change I was going to go ahead and replace that. I did the C101 refresh and checked the fuse with a multimeter and even swapped it, it was good. Still need to do dipstick area grounds and a couple other you mentioned. But I’m about out of ideas. Praying that works. I love having an XJ again I just want to be able to move out of people’s way haha.

  34. clarification here. You push the button and then push the cable housing AWAY from the throttle body. Release button. Open throttle all the way to set it.

    1. Yes. Push button slide the plunger into the housing then release button then open throttle and I got just a little click like it hit it’s first notch. After that it doesn’t move anymore.

      1. Ok so I feel like an idiot but I wanted to let you know. I was replacing my battery cables since they both had a lot of wire showing. And when I looked at the TPS again. Previous owner must have messed with it and the little sensor pedal, was actually on top of the throttle pin… So I pulled the sensor out and put it underneath the throttle pin. Came up 4.62v I set it to .786v and voila. Surprised at how well and smooth a 31 year old Jeep shifts thanks so much for your site. It definitely helps a ton!

  35. I used an mt2500 on my 90 renix. Under the tips menu it reads as follows for the TPS.

    If TPS voltages incorrect adjust TPS to obtain .65v with throttle closed.

    Why do you recommend .84v?


      1. Thank you. Just one more question. My tps v reads 4.49. Should it be higher.

        Thanks in advance.

  36. Hey bud, it’s been a little over a year and I’m finally getting time to mess with this 89 Comanche.

    Replaced distributor, plugs, and wires. Then cleaned the throttle body and replaced the TPS.
    After doing this, it runs awesome except for I still have the shifting problem where drive does nothing but stay in overdrive. I cleaned the dip stick and the manifold grounds very good with no change.

    The crazy part is that I drove it around a little and while messing with the gears, it randomly started working in drive like it’s supposed to. But once the key was turned off and turned back on it wouldn’t do it again. This exact same thing happened last year also. Do I need to be hunting down a weak ground or is this a sign of the TCU going bad?

  37. Hi cruiser, thanks for all the great work you do for the Renix community. I have a 91 Renix 4.0 and trying to chase down a problem where it stumbles at 55mph. I have performed tips 1,3,4,5 and 11. Just finished with step 8 (clean/adjust TPS). On the flat plug I measured ref volts at 4.88 and output at .76. Calculations say adjust it to .8296 (.83) which I did. Started it up and it started idling pretty high (as you mention in the tip). I reset the probes and restarted it but can’t get it to bring the idle down even if I adjust it fully clockwise. The idle never drops down far enough. Unfortunately I don’t have a tachometer so I can’t see what it’s actually at but it’s audibly turning much higher rpm’s than before I cleaned the TPS. Any suggestions as to what to look at next? Thanks again – Paul

    1. Cruiser, you actually helped me with this back in early June when I PM’d you in email. Turned out my idle wasn’t coming down due to the throttle blade being way out of adjustment. Once that was set correctly, I was able to adjust the TPS to the correct output volts and it is running sweet now. Thanks for all your help.

  38. upgraded to the 88 ECU and still like the way it runs better than before, but wonder if the shifting could be smoother. Is it possible the new computer is producing a different reference voltage than the new one and the tps needs to be readjusted? Also how would I know if I had the 88 or later TCU that you had mentioned on another thread is a good thing to have? Thanks!

    1. The smoothness of the shift is regulated by the throttle valve cable. You’ll never get that 21st century shift feel out of your Jeep.

      There are part numbers on the TCUs. You can do an internet search for the part number to determine the year.

      Am I correct in assuming you have completed Tips 1 through 5?

  39. Gotcha. I went ahead and checked the output voltage after installing the 746 injectors, (Wow, what a difference!) because it idled kinda high. wouldn’t you know it, not 17 percent, (guess the new computer put out a different #). Turns out my old clogged up injectors were forcing me to keep the idle a little high as it would stumble when coming to a quick stop sometimes, and I was able to close the throttle butterfly valve down a little further using a sticky note to get my .003″, then I readjusted the tps. Now it runs like a top!

    I have done the majority of your tips except some of the more intense ones like distributor indexing and #1 TDC, valve cover mod and a couple others i’m probably forgetting. I’ll have to look into the TCU #. Thanks for all your help, I’ve been a little short on cash lately but I WILL be making a donation ASAP, I probably would have sold this thing a long time ago if I had never found your website! Cheers!

  40. Yeah it does, I was chasing the high idle for months before I finally broke down and did “restoring throttle valve adjustment” mine was open waaay too far and the screw had loctite on it. There was a whole lotta stupid done to this poor jeep, but I am slowly reviving her!

  41. That’s what we do sometimes. Undo stupid. That’s why we spend a few minutes making sure what’s NOT wrong and establishing a baseline.
    Good job on your part.

  42. Eventually you just get tired of bashing your head against the wall and try to learn to work smart. This is my first car and I knew nothing about cars before I got it, so it’s been a great teacher, haha!

    Anyway, my sister’s jeep that I was emailing you about had some really weird behavior when I was going through all these steps to do with the idle and getting the engine to run right… her’s was the opposite of mine, the butterfly screw was backed out so far that it had over an 1/8th” gap between it and the tab that it’s supposed to rest against, and then someone wrapped electrical tape around the tab to try to close the gap… It didn’t look like it had worn into the walls of the throttle body, but there was a chip out of the “valve plate” (idk what to call it). Throttle body is clean.

    The TPS also acted weird, whenever I I had it adjusted right it had really inconsistent behavior when starting, one time it would run good, the next it would rev up to 2 or 3000 rpm. I had the issue of the exremely high idle that you mention in the tps tip here, so i tried to adjust it down with the engine running and it didn’t respond, ( the tab on the tps was in the correct position), the voltage would change a little bit but not with any consistency to the amount of movement, and the idle would not change. Eventually I adjusted it a little bit lower than what the numbers said it should be because it gave me consistent behavior on the idle itself, Which is a bit too low.

    I had to do the same thing with the butterfly screw, I just had to make a ton of adjustments in an attempt to get consistent behavior when starting. I think it ended up being further closed than .003″. The problem from the beginning was that it would not start up again within about 5 minutes of shutting it off once hot. The PO thought the problem was “heat soak” so he wrapped the injectors and fuel rail with reflective stuff to try to cure it, he also said that the e fan would not come on, which was true. I actually thought the material the reflective stuff was made from seemed like it would retain heat, so I took it off. After cleaning an insane amount of corrosion out of the e fan relay receptacle, and replacing the e fan switch in the radiator, the fan comes on. The fuel injectors are also not stock, I couldn’t see a # on them, but they’re the same yellow as the Bosch ones so they might me Bosch, but they are not 746’s. I wonder if they are incorrect for the xj.

    The throttle body to MAP sensor hose is not original, it looks like someone did a super half-ass version of your fix, I plan on doing it properly and believe it to be the main culprit of most issues. However the part #’s you provided on that tip did not work for me?

    She now has the jeep in her possession and the current behavior is this; It starts fine cold, but cranks for about 4-5 seconds before starting, (I noticed my crank time is much shorter after installing 746 injectors). It will start back up if you start it immediately after shutting it off, but if you wait about a minute it will not fire up for about another 2-3 minutes. once you can get it to start, it will start and then die, the rps are too low. But, if you give it a little gas before the rps drop too low, it will run fine but stumble until you get moving again. if you wait about 5-8 minutes it runs “normal”. It also smells like it’s running pretty rich, (which I would attribute to the TB-Map hose) and feels like it lacks power and especially torque until you reach about 30-35 MPH.

    I think that’s about averything, other than the power windows and lock do not all work, ( don’t know if it’s motors or what, but I’m gonna gonna do the instrument clusterfuck ground upgrade which is a good one, and probably also headlight harness upgrade which is awesome.

    She just had her first baby, so she will need a reliable family vehicle so I would like to get these issues resolved, my plan of attack is this.

    1. TB-MAP hose
    2. Possibly replace TB
    3. New TPS?
    4. 746 or even possibly install my old injectors after cleaning them

    Any other thoughts? Sorry for the EXTREMELY long comment. Thanks.

    1. You probably have injectors for a later model 4.0 and I’ll bet they’re bleeding pressure off when the car is turned off.
      That can be tested.

  43. You’re doing a great job and sticking with it. has great refurbished injectors at a very fair price. I’ve used numerous sets on both Renix 4.0s and the 5.2 V8s.
    You have checked the intake manifold bolts, right?
    Here’s what I would do first.

    1. TB to MAP hose fix.
    2. 746 injectors.
    3. Test TPS.
    4. I’m guessing the throttle body will be fine.
    You’re correcting a whole bunch of crap some knucklehead did. It ain’t easy, but you have to leave no stone unturned.

  44. You’re probably right, they are the same bulbous shape as the renix injectors. How do you test if they are retaining pressure? Thanks it has been hard finding and diagnosing all of the stupidity… I haven’t checked the manifold bolts, I was too lazy to take the skidplate off to get to the bottom ones with all the other stuff I had to fix asap, I will have to check those. Thanks I will do everything in the order you mentioned, is there any way to find current part #’s for the MAP hose?

  45. Okay thank you. I must have been unclear, I meant the parts for your MAP hose upgrade, the part #’s didn’t work. I can probably figure it out by the size of the TB orifice. Do you happen to know the size of the vacuum tubing off the top of your head?

  46. I have an 88 XJ 4.0 that won’t shift. It has been suggested my problem might lie with the TPS. I have read over the instructions above but before doing so, I disconnected the 4 pronged wiring clip coming from the TPS. Is this an issue I should be aware of?

  47. Thank you for all the information, I have an 87 that just started shifting extremely late. Has all the gears but have to hit 4500 rpm to shift. Checked the flat tp connector. But was unsure on the other. I will check it this weekend. Shifted fine until it was left with the hood open by mistake during a rain storm oddly enough.

  48. Headed tomorrow to work on it ( my aren’t sheep) Dad stated it idled fast when he started it also after leaving the hood open. Will let you know how it goes, thank you for sharing all this great information.

    1. Tp fixed the issue, hasn’t shifted this good in a long time. I am going to work on cleaning up and updating all the grounds like you suggest. Especially that main connector. I would like to also change that fiasco of heater hoses that go to the tank, but noticed your link doesn’t work. Do you have any suggestions ? Another weird thing with this is the plastic around the headlight switch got brittle and broke. Wondering if the high resistance from bad grounds caused excessive heat, any suggestions ?

  49. Good job!! Yes, continue with Tip 5 for sure.

    I never wrote the heater hose deal.

    How is your current radiator? Possibly in need of replacement?

    And your suspicions about the headlight switch are right on.

  50. Radiator is in great shape, it’s an 87 but only has 60k miles on it, no corrosion or leaks . Only cooling system issue is the temp gauge doesn’t work.have any suggestions on a dash repair? I was just going to epoxy a new piece in its place, but looks like a royal pain.

  51. If the radiator is in great shape, you can add a filler neck in the upper radiator hose. Eliminate the pressure bottle and put a reservoir in it’s place. Change to 97 and later heater hoses and eliminate the heater control valve while capping off it’s vacuum line.

    Dash mat? LOL.

  52. I was meaning the dash where the headlight switch mounts, since it got hot and the plastic broke away , I need to put something in there to screw the light switch back in place. Next weekend going to do the ground repairs it start getting it serviced up for winter, even though mom probably shouldn’t be driving, and might only put a couple hundred miles on it over the next 6 months,

  53. That’s pretty hot for a headlight switch!! Unfortunately that part of the dash isn’t replaceable. You putting a new switch in also? Doing a supplemental harness?

  54. Have a new switch for it already, the connector was in good shape, what supplemental harness are you referring to ?

  55. I had the same issue with my ’87 XJ and it seemed more like plain fatigue of the plastic (several other places on the dash face tend to break with little effort). Since the knob comes off easily (little button on the switch body and out it comes) and there was a few little bits of the edge at the bottom of the hole, I found a washer that nestled in the bottom and made the hole big enough for the threaded part of the switch and glued it – the washer – in. put the nut back on and slipped the knob shaft back in. It wasn’t too bad with just the bottom panel of the dash off. Oh, and I am pretty gentle with the light switch now, just to be sure! haha
    Now if I could have the same luck you had with the shifting . . .

  56. Cruiser,

    Is the 17% ratio still the same for the 2.5L with automatic transmission? Been having very rough idle and trouble starting. Adjusting the idle screw on the TBI cable seemed to help some All grounds have been refreshed. Thanks for all you do, I’ve done quite a few of your tips on my ‘89 Manche and ‘90 Wagoneer limited.

    1. I’m not sure about the spec on that and I don’t have my book handy. Rough idle is generally not a TPS issue.
      Check to see if your intake and exhaust fasteners are all there and tight.

      Also inspect the 2 hoses that go into the intake manifold right below the throttle body. Notorious for leaking.

  57. I’m getting 0.50V A-B, 0.32Ohms B-negative battery, and 0.01V B-C…I’m guessing that means it’s bad

  58. Cruiser really appreciate the time it took for this info to be posted. Great stuff.
    My 89 XJ has been shifting funny and the rpms acting up to try adjusting my TPS. The voltage with the key on while testing the flat connector fluctuates from roughly 4.20vdc to 4.75vdc is this normal. If I unplug the connector and test the harness side with key on I get consistent 5.00vdc. I also can get the percentages to even out between the flat connector and the square connector. If I dial the flat on in at 17% then the square one is way above 83% and vis versa.
    I’ve been thru the first 7 steps. Just wanted an opinion on the voltage fluctuations before I throw a new TPS at it. THANKS!

      1. Hey Cruiser, I need help and I figured you’re the guy. I’ll try to be as clear as possible. I have an ‘89 XJ Waggy with the 4.0 and AT. I bought it not running with a blown transfer case. Since acquiring it, I have replaced the t-case, done plugs, wires, cap, valve cover gasket, switched to open cooling via your method, checked and refreshed all the grounds. It had a persistent high idle so I decided to swap the TPS. Upon attempting to swap the TPS one of the bolts broke so I acquired another throttle body. While replacing that I cleaned the new one…it’s now beautiful. I changed the gasket and reinstalled. I didn’t originally know the TPS needed adjustment so I just tossed it on and rolled. Anyway, my idle is good running at about 800 but since all of this, the Jeep can’t seem to find its shift points. So, I’m assuming I need to adjust the TPS correctly but I’m really really confused. I’ve read some people adjust from the 4 pin connector. I tried your way today by probing the 3 pin connector. Now I am probing the backside of the connector from the engine harness, not the connector on the TPS itself. With positive in A and negative in B I get a reference of 4.90 volts but when I move the positive to C and leave the negative in B, still on the back side of the connector coming from the harness I get a 0 reading and no amount of adjustment changes this.

        Furthermore, when I back probe the 4 pin connector from the TPS itself (this was in some YouTube video), I get basically the same thing. Reference voltage reads 4.87 but B to C only reads 1.95 no matter how much I adjust when it’s supposed to get to something like 3.88.

        Am I doing something wrong? Am I not testing at the correct side of the plug or the correct plug? Is it possible that the TPS is bad and causing the bad readings?

        Thanks in advance.

  59. Should the “D” connector on the Transmission side of the TPS measure close to 0 ohms as well (connector to negative post of the battery – engine off) or does it get its ground through some other source once the engine is started? I am working through all of your tips and while my throttle side is great, the transmission side is reading 6Kohm between this connector and the post.

    Thanks in advance!

  60. Hey Cruiser, maybe you can chime in.
    (Thanks for all your knowledge and help in advance)
    I’m in the attempts of replacing what I think is a faulty TPS on my 89 manual. Upon start up, idle climbs from normal range then slowly reaches about 2000rpms then I freak out and shit her off.

    I can probe with the key off and get no fluctuation from my ohm reading given with the key off and shaking things up. But for the life of me I am not getting a reading when probing A and B etc when the key is positioned on. I’ve tried two different readers and nothing. What would be a safe output to start off with if I just replace the sensor. Hopefully that made some sense.

      1. Sure did! I was able to unsnap the little plastic tabs and get my meter shoved in properly to get readings but they’re nowhere near normal, what I feel like is normal. (AB 4.91, around a 4.62 for BC, and I read on another post on Comanche Club a member stated for AC output should be 8 but I get like 5.2) I haven’t replaced it yet I’m a little hesitant/don’t wanna mess something up lol. Thanks for the response too, it’s an honor.

        1. No fears!! Just be sure you get the tang of the TPS on the correct side of the linkage. You’ll understand it when you see it.
          I’m unsure about the AC comment someone said on CC. Disregard that.

  61. ’90. No C101. Transmission is shifting perfectly. I started this project as a “refresh”, not to fix a problem.

  62. I can obtain the correct percentage with both sides of the tps but once I adjust the engine side, the transmission side is off again. It wants to be 3.9 V but once engine side is adjusted it reads 3.74 Is this acceptable? I wanted to get the transmission part adjusted thinking it might be the cause of the occasional slam I have been feeling while driving recently.

  63. Understood. Recently I replaced my starter and alternator and that is when the slamming feeling started. I know they can’t be related. There was a large bolt above the starter, I believe it was a bell housing mounting bolt, that was finger tight, so I snugged it up without going crazy on the torque. I don’t think it’s that either but thought I’d mention it. I checked the torque converter bolts, tight. transmission fluid level is good, shifts smooth. Any ideas on why I’m getting this sudden slamming feeling from under the jeep? doesn’t happen at any particular speed, or under any particular circumstance, just random. TCM?

  64. Guess what year xj I drive? Haha! So the only two bolts I can get at are the lower two, one was tight, the other was the loose one. The only other one I could see was above the cps and will require a female torx socket and a ton of extensions with a u joint. (unless you know a better way) How many other bolts are there? Is there a torque spec, or do they just need to be tight? Thanks for the help, as always.

  65. I forgot to mention there were several empty bolt holes in the housing itself, but they looked too far back to be mounting bolts, I don’t know if they’re meant to have a bolt in them or not. I also have a fairly large weird shaped hole in the bell housing, I think all the torque converter bolts are there (4?) though, which I’ve heard can blast through the housing when they fall out. I also don’t have a cover for the housing, don’t know how much that matters? sorry for the rant.

  66. On mine, it was obvious that someone had done an engine swap. A sloppy one. This was not a factory issue by any means.

    You are correct about reaching the upper bolts. The best way to reach them is by lowering the rear crossmember for access. If those bolts are loose, remove them one at a time and replace with normal hex headed ones.

    Check the torque converter bolts NOW. Remove one of the 4 at a time. Clean the threads on a wire wheel, apply Loctite and tighten it back in. The engine can be rotated with a 3/4″ socket on the front pulley. Trust nothing has been done correctly at this point.

    As for which bolts go where,take a look at another Jeep. I don’t know of any diagram floating around.

  67. Thank you, I will get this done asap and before driving, I definitely wanna get this resolved before I cause any damage. I guess it could make sense that it’d start clunking right after I tightened one bolt if others are loose. Will report back with either success or failure, thanks again!

  68. So I was able to get at the top torx bolts for the bellhousing from the top, at the back of the engine compartment, using a 3/8 ratcheting wrench.

    The bolt on the passenger side was loose and the driver’s side was tight, same as the bottom bolts. The driver’s side was tight enough I didn’t wanna try to break it free with the 3/8 12 point, so I left them both to explore my options.

    I don’t think I have the clearance to back them all the way out to replace them with hex head bolts, unless I lower the transmission. So, since I can access them from the top, what I want to do is just get an E12 ratcheting wrench and tighten them up with a cheater bar. Thoughts?

    Should I loosen all the bolts and torque them evenly or just tighten this upper one? Do I need to find the torque spec, or is “tight” good enough?


  69. “Tight” is good enough. If you lower the trans crossmember, you get a better shot at the upper bolts.

    Go buy a gallon of Dex/Merc ATF ONLY. Drain the trans and put the gallon in. Drive it.

  70. Well I tightened that bolt up with the 12 point wrench as much as I felt I could without risking messing the head up, while I wait for the right wrench to arrive at the local napa. I had to drive it 80 miles today and didn’t feel the slam once, must have been the bellhousing! Thanks!

  71. Well, I’ve been feeling the slamming feeling again 🙁 it seems to happen after I come up to speed and the transmission shifts into overdrive, I can’t remember if it’s ever happened in a lower gear, but I think it has. The jeep has always been a little hesitant to shift into overdrive, kind of hangs out at the top of third until I gain another 5 mph or so, or if I give the gas pedal a little jab. It’s also always been a bit hesitant to downshift at about 50-55 at the base of a steep hill near my house, same thing, give the gas pedal a jab and she will shift, but usually kind of hard on the hill.

    I double checked the bellhousing bolts and they are still tight, fluid level is good, so is color and smell. Nothing I can see that may be bottoming out, or contacting anything else under the jeep.

    I am beginning to suspect a transmission solenoid is sticking or just not operating at the right time. Could it be the torque converter lockup solenoid? I would suspect it above the others because every gear shifts pretty smoothly, but the slamming feeling always happens AFTER the transmission shifts. My understanding of transmissions is VERY limited. Thanks for any insight!

    1. Test the trans side of the TPS. Could be bad. I’m assuming you have done the ground refreshing at the engine dipstick tube stud.
      Have you done Tip 10? Changed the tranny fluid with dex/Merc? Only need to drain and fill.

  72. I checked the trans side of the TPS when I first noticed the problem in july and I was able to obtain the correct voltage, once I readjusted the engine side, the transmission side was only off target by 0.16 V.

    I have done the dipstick ground refresh as well as tip 10. I have not changed the tranny fluid yet, I guess I should start there. There is no need to change the filter, just drain and fill?

  73. Well I changed the fluid and it definitely seems to shift smoother, seems to have snappier shifting response when I give it some gas, and deals better with being stuck at kind of an odd speed, like when stuck behind a bad driver. Just better to drive overall. I wonder if it had the wrong type of fluid in it before. I haven’t felt the slam since, but only drove about 15 miles to get the fluid hot enough to check. I’m a tiny bit overfilled at the moment, I’ll get the level right and keep you posted on the status of the slam after some more driving!

  74. Okay, will do. I did feel the slam yesterday right when it shifted into overdrive. If the problem persists, should I suspect the solenoid responsible for OD? Do you know of a way to test the TCM?

    One more thing, I only got 2.5 quarts out of the transmission, I had the rear of the vehicle facing downhill on the slightly sloped driveway, and jacked the front up, is this the best way to get the most fluid out?

  75. Hey Cruiser, so I have an ‘87 Comanche I bought a while back. 4.0 automatic, factory 2wd truck. When I bought it, the motor had been rebuilt and not long after it had been rebuilt the tranny went out. When I had bought it, it didn’t run and they had stuck a tranny out of a ‘97 and up Cherokee. After doing the 4wd swap and getting a tranny out of a Renix Cherokee, and a new CPS, it now runs. But it idles rough, and starts back firing on slow acceleration.

    So after talking around and asking questions, I thought it may have been the TPS. Cause I’m also having problems with the transmission not wanting to take off in first when it’s in drive, but it can be manually shifted.

    But while doing the TPS testing/adjustment I can get a reference reading (4.45) but I cannot get and output reading. When testing B and C on the flat plug, all I get is 0 or sometimes it will flip to .01. I also bought a new TPS, nothing changed. I have also cleaned the C101 connector like you have.

    Any suggestions?

  76. What’s a common voltage for A positive to B ground? I’m getting 1.73 for reference. Prior to installing a new CPS I remember getting something in the 4.7 range. Does that mean my CPS is shit?

    It’s a NAPA CPS.???

    1. Well it is running better adjusting TPS to .17 of the reference voltage: 1.73 = .29, but still idling a little rough. I’ll check the CPS for the .5 voltage cranking it over unplugged, and then if the CPS is good move forward with indexing the dizzy. Good to know I can bypass EGR, but it is now working. After going through cruiser steps 1 to 5 (refreshing all wiring – checking all factory connections, wrapping in new tape, new dialectical grease, wire loom, tie downs – took 3 days labor), all new vacuum hoses and swapping for the Volvo injectors my renix jeep is running much stronger, but like I said just a little rough idle (at 100 miles of a 500 mile braking in new motor). Sensor grounds look good. Next project: indexing the distributor at top center and hopefully a smoother idle.

    2. cPS has nothing to do with TPS. CPS generates its own voltage.

      Are you testing the flat connector of the TPS?
      Reference voltage is generally just a tad less than 5 volts.

      1. Yes I’m testing the flat connector with ABC embossed. I’d share a picture if I could. Multimeter is set to 20v. This is a new TPS. I have a lot of spare parts from firing the parts cannon before discovering cruiser54. Maybe I’ll throw the old TPS in and see what voltage it throws. (I’m gonna click the donate button here soon cruiser- I really appreciate your time).

        I didn’t redo the factory connections for the ground sensors or any other factory solder connections wrapped in duct tape in the engine bay harness. I unwrapped the old duct tape and cleaned the connections, then wrapped them tightly with electrical tape. On inspection all these factory solders look good so I wrapped them individually with electrical tape and moved forward.

        It’s bewildering why the A to B would give 1.73 but setting TPS to .29 (1.73x.17) does have the jeep running better than it was.

        1. Ha ha. The rough idle was my dumb ass – had 2 injector connectors on the wrong injectors. 5 & 6 were backwards. Just drove the jeep up the canyon and back. It’s running noticeably better after completing steps 1 to 5, the Volvo injectors, etc. That TPS voltage thing is so weird. I’ll check it again soon. Regardless, my 89 XJ is running good.

      1. Hello Cruiser 54 or appreciate your knowledge and hard work enormously. the problem I’m having is is I can’t get a normal reference voltage from the TPS on the transmission side the reference voltage is 0.51 the transmission side of the TPS does not appear to be receiving any ground from the tcu you you when checking terminal D3 3 ground the tps I’m getting nothing. Does this mean the tcu is is not working or is there some other reason that would cause there to be no ground?

  77. Im having a crank no start problem on my 90 laredo 4.0 Ive done just about every 1 of the tips other than tps testing it seems someone cut the wire connectors of and wired the tps straight to the harness i can get it to run ‘shitty’ by running a wire from the negative battery terminal to the ground leg of the power laych relay but without the ground wire it will crank and start just to immediately die any suggestions
    And ive looked around for another 1 to get the tps connectors and whitch 1s go where but no luck jeeps are hard to come by where im from and nobody will pop the hood for ya to yake a pic for reference

  78. I was troubleshooting a no-start and in the process removed the TPS and reinstalled.. it ended up being the C101 connection. Anyhow, my acceleration sputters and thought I probably needed to adjust the TPS. so, i was back-probing, with safety-pins because i couldn’t get a reading, any may have created a short. My question is, did i fry the computer or TPS?

  79. Hi Cruiser54, I have had a high idle ever since I have had this jeep. When cold, it idles at 1000 rpm once it starts to warm up it idles between 1250 and 1500rpm. I replaced the TPS twice and did the measurements and calculations each time. This had no effect. I did a smoke vacuum test a few months ago and had some leaks at the throttle body where it meets the manifold, some at the harness. I put a new gasket at the body and a hew upper and lower vacuum harness. I also had leak coming out of the EGR valve this is where most of the smoke was escaping. I cannot replace this valve because is no longer made for the 1988 4.0L. would you suspect the leak at the egr valve causing the high idle?

  80. Hi Cruiser, Thanks for running this website for the community! To contribute something back, on my ’88 Cherokee I got a high idle of 3000 RPM after making the TPS adjustment to 17% of reference voltage. I shut off the car, disconnected the battery cable to make the ECU forget, reconnected it, and it worked! My sample size is 1 vehicle, but it may work for others to get their idle back to normal.

  81. First off like everyone else I want to thank Cruiser54 for what he does for the Renix community. That being said I got into the Renix game just about 10 months ago. 258’s had been my life story until now. Im in love, didn’t care for the Mopar HO’s much and had nothing but trouble and now I know why. Anyway, stroked jeep doesn’t seem to be a thing anymore for 60mm throttle bodies, but I think I found us all a place, its on the return trip now. I’ll let everyone know how it goes. Its called Maxbore out of Fla. anyway I know you supposedly got instructions from Stroked jeep on the TPS. This new vendor I found does everything so he probably doesn’t know much. What would be the adjustments needed Cruiser? Saw you did this mod in a forum maybe 13 years ago. Thanks!

  82. Scratching my head on what I thought was a throttle body problem from the previous owner dinking around where he shouldn’t. When cold, if you rapidly depress and release the accelerator, the engine will “bog” or “hesitate” before revving. Like a carburetor that has the wrong fueling, or a distributor somewhat off time. Being EFI and the ECU taking care of the timing, I’m at a loss here and hoping for some wisdom. I have done tips 1, 3, 4, 5, 8, 11, 14, and 27 (done previously, looks to be done very well).

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