Renix ECU Connector Refreshing

Renix ECU Mounting

Many times, when other fixes have failed, it becomes necessary to eliminate the ECU to harness connections as a cause. This requires removing the ECU. Up under the dash, to the right of the steering column is the ECU mounted to a black bracket. The bracket is held in place by two 10mm nuts to the underside of the dash. It’s most easily removed using a ratcheting wrench but a socket will work.

Once you get the ECU down, unplug the two harness connectors from it. Visually inspect the connectors and pins.

Using a good quality electronics cleaner, liberally spray both of the harness ends and the ECU pin area.

Now, take a small pick or a dental tool and go to the harness connectors. Using the tool, tweak each female receptacle in the harness plugs so they will grasp the ECU pins more tightly.

Plug the harnesses back on to the ECU and reinstall it.

Revised 1-31-2016

16 thoughts on “Renix ECU Connector Refreshing”

  1. On the one harness coming into the ECU I have a bare, uninsulated wire that doesn’t seem to be connected to anything. Is this a ground, and if so where should I connect it? Btw… thanks for all of these tips!

  2. So I have a really weird issue if I plug the ecu in and keep the wires straight it won’t start but if I bend the wires making a right angle it fires and stalls but if I twist the computer two times and fold the wires over it fires and idles fine but as soon as u set the ecu Down it stalls

  3. Hey cruiser, did you ever came across a pink color coded ecu? Reference S 101144202 A -53005624. European market model, ‘90 model year. I’m chasing my tail trying to get in closed loop but everything i try seems to have the same outcome: crashing into a brickwall. Good grounds everywhere, bosch and ntk sensors tested, absolutely zero air leaks on intake and exhaust, 2 map sensors, new coolant and intake temp sensors… this XJ never had an o2 sensor until i got my hands on it, only a M18 bolt in place of the sensor and it does not look like a hack its hollow on the inside, factory built without cat (because euro regulations). Burns fine but maybe a little bit on the lean side, runs pretty much fine, etc. I’m finally thinking… maybe this ecu does not have closed loop because it never had a catalyst in mind?

    1. What tester are you using?
      Can you see what the O2 sensor is doing?
      It should go from .1 to 4.9 volts quite rapidly or “rich/lean, rich/lean” very fast.

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