Cruiser’s Mostly Renix Tips Index

Renix tool kit 2

Cruiser’s Mostly Renix Tips

Technical DIY instructions covering common issues on the Renix XJ Cherokees and MJ Comanches (1987-1990). Preventative and proactive procedures to save you headaches, time, and money.

Many of these tips were provided to me and my buddy Joe by JeepTech when I was Service Manager/Shop Foreman at a Jeep dealer from 1980 through 1992. That’s what “The Book” is all about. Our notes from back in the day. Right from the Field Service engineers. Thanks Lonnie and Big Al!!  Most were never published, until now.

Tips 1 through 5 are a great place to begin before chasing your tail with parts replacements on your 87 and 88 Jeeps.  These are pretty much “haftas” in Renix Jeep ownership. You can skip Tip 2 if you have an 89 or 90. But, do the Tips first……….Avoid firing the “parts cannon” at your Jeep!!!!!!!parts cannon 2


The next priorities are Tips 11, 13, 31, 25 and 26

A simple multimeter is handy along with a few other basic tools……so dive in and get to know your Renix Jeep.

Some Tips also transfer to later years, or the techniques can be adapted.


1 – Ground refreshing

2 – C101 connector refreshing

3 – Connector and relay/receptacle refreshing

4 – Coil/ICM contacts

5 – Checking sensor grounds

6 – Sensor ground upgrade

7 – CPS testing and adjusting

8 – TPS testing and adjusting

9 – ECU connector refreshing

10 – Trans plug connector refreshing

11 – Throttle body and IAC cleaning

12 – Setting your 4.0 to #1 TDC

13 – Renix Distributor indexing

14 – Restoring Throttle Butterfly Adjustment

15 – Rear main seal diagnosis

16 – Vacuum test for exhaust restriction

17 – HO engine into Renix

18 – Improving the instrument panel ground

19 – Headlight harness installation

20 – 4WD shifting tips

21 – Renix EGR valve test

22 – Renix vacuum harnesses

23 – CPS timing advance mod

24 – 4.0 Engine date codes

25 – Valve cover mod ***NOW WITH VIDEO***

26 – Oil Filler cap Mod

27 – C101 Connector Elimination ***NOW WITH VIDEO***

28-Improving blower motor performance

29-Improving the fuel pump ground

30-Adding the Sentinel Headlamp feature

31-Throttle body to MAP hose upgrade

32-Renix metric oil filter to SAE filter

33-Converting to an open cooling system

34-Eliminating the Heater Control Valve

35-Reducing cabin wind noise

36-Bypassing the Power/Comfort switch

37-Best injectors for Renix

38-Improving the wiper motor ground

39-4.0 Engine Removal

40-More power for your 87 and 88 4.0 ***VIDEO***

41- Easily track down and repair  ENGINE VACUUM LEAKS





True tales from "The Book"