Failed ignition control modules

[Htchevyii]

Just curious as to how many have experienced a ICM failure? The only time the MJ has been towed that I can remember in the last 30 years, (except for the lake incident, not the trucks fault), was when the ICM failed about 20 years ago.  Fast forward to now. I attempted to drive my "new" 1989 XJ  to work on Monday. I made it about a mile and the engine shut off and wouldn't restart. 

Everyone's always talking CPS so I went ahead and installed an NTK and did the bolt hole mod. I've replaced a few of them just because I was doing a clutch or something, but have yet to have a CPS failure, (in 30 years). Just curious as to if many others have had ICM failures.

 

To be fair, I always replace the ICM and coil, so I suppose the coil could be the problem. One more thing, for some reason it is currently very hard to find a replacement ICM. Rock Auto doesn't show any brands available. Nothing at Napa and most online suppliers showed out of stock. I did disregard  unknown  brands with made up sounding names. The local O'Reilly had 1x Masterpro in stock and said that it was all that they could get and there weren't any more in their warehouse. I carry a spare, (that I used on the XJ) so I went ahead and bought it, even though I usually opt for a better brand. 

[cruiser54]

ICM/coil failures are extremely rare. 

[oleskool]

My 89' had a strange situation similar to that where it would crank up cold just fine but after about 15 - 20 minutes of running it would shut off and not crank up for 20-30 minutes.  Long story short after checking many other culprits, I remembered another similar issue I had with another jeep where the ICM heated up due to an internal short and would cut out power after it heated up to much internally.  The next time it shut off as mentioned above I poured water over the ICM and it fired right back up.  

[cruiser54]

This Tip has the potential to repair bad connections which result in excess heat.

 

CRUISER'S MOSTLY RENIX TIPS

RENIX ICU/COIL CONTACT REFRESHING

OCTOBER 30, 2015 SALAD 33 COMMENTS EDIT

The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.

The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner and some fine sandpaper.

Squeeze the springy contacts closer together with some needle nose pliers. Apply some OxGard to the contacts. Bolt the coil back on to the ICU.

While you’re right there, unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier.

I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.

[ratrapp]

I worked at a jeep/chrysler dealer from 96-02 and we only seen 1 renix icm fail.I thought that was pretty good.

[Htchevyii]

Maybe I'm just lucky. The first one failed on the MJ when it was about 10 years old, so I guess the Mopar replacement has lasted 25 years. The old one out of the XJ said Renix on it, so I guess it might be original. The contacts were not corroded, (high desert rig). I've still never had a bad CPS though.🤔