OK, can't resist. Jeep ran great today like it should. My confidence is building. Put in new plugs.....why not?
DFlintstone, sorry for any confusion. I always thought ICM when after some research most called it ICU.
Thanks cruiser54, I will report.
Steve

 

No sweat Steve. I myself have an especially hard time there. What threw me is allot might call the ECU, an ICM. (electronic control module), (91, and on IS a PCM). Powertrain Control Module. So I thought you meant the puter'.

Again great info, great thread. So going back and doing a more through job of cleaning the coil to ign module thing, did indeed seem to solve it.
And again we are supper lucky to have Cruiser here. ECU grounds at the dipstick (g104), and if I follow correctly, so does the oh poo... was Icm? The spark thing, grounds there as well.

UNIT! ignition control unit...

 

OK campers, I'm calling it 'GOOD'. Things are back to normal (or better), not a hiccup, stall out or hard start. Even gas gauge works better which I'm sure is due to cleaning all the grounds.
I'm not positive about my success from cleaning ICU mounting bracket bolts but I do know that the ICU/coil contacts were cleaned twice before. As with my radio and music gear 90% of problems are electrical contacts or grounds and I'm pretty good at cleaning. Soooo, it's a 'definite maybe'.
Thankful that I found this forum and big thank you to cruiser54 for your Renix Tips. I'm a die hard DIY'er and you saved my back side.
If anything else goes wrong, and of course it will, I'm certain it won't be the new TPS I installed (naturally I have a manual trans).
Thanks again all,
Steve
Talent, OR.

 

Glad to hear you gotr'...Btw, I'm "right over the hill" West of you, not far from Hiouchi Hamlet!

 

Good news. Keep us posted.

 

It always feels good when I can fix something, especially this rather complex beast. Fortunately we have a third vehicle so I could put the wrench down and walk away when I got to 'that place'.
Nice area Hiouchi, we go through there when we go to Gold Beach. Years ago I new a guitar player with the group Detour that lives/lived there.
Take care.

 

I thought I could answer each post separately but apparently not.
Pete, I woke up with a DOH! slap to my forehead. I could have tested my theory about the ICU mounting bracket by putting a piece of wood under the ICU (without bolting it down) and see if it will start. I'll try that when it stops raining because I just gotta know.
What do you think?
Steve

 

I wanna know. Send the rain down to Arizona will ya?

 

I had a window between rain yesterday (sorry Pete, gotta keep all we can) but after all the wrenching I've done on this I just couldn't bring myself to pop the hood. But today I had to know so unbolted the ICU from the mounting brackets, put a piece of 2x4 underneath, and....and.......it started up fine. Oh well, it was a possibility. The fix must have been better cleaning/tweaking of the ICU to coil contacts plus the DeoxIt and now dielectric grease. Whatever, it's done, fixed, finished.....until next time.
Steve in Oregon

 

I changed my instructions:



Renix Jeep ICU/Coil contact refreshing
　
　

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 needlenose pliers. 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.

　

Revised 04-04-2013

 

Yes, this an old post but it was mine and I feel I owe an update since I received some good help with my problem.
Cleaning the coil contacts was on the right track but the 'next time' happened. Long story short: ICM - ICM - ICM. When it actually backfired.....I knew. Replaced it 5/13 and no problem since.
Keep 'em running,
Steve

 

So, I have just gone through a similar situation as Steve. First the jeep had an overheating problem and just before Christmas I found out it was a cracked head. Just recently I scraped up enough time/money to replace the head and everything worked great! I did a five mile test drive with no issues at all. The next day when I went to drive it, there was a no start issue.

The first thing I went to was the CPS because I have had this issue in the past. the voltage was below .2 VAC so I replaced it. The new was at about .25 VAC so I drilled out the mounting holes until I got above .5 VAC. The Jeep, again, ran great, for about 1/2 mile.

I have free towing so I called a truck and had it brought back to the house. The CPS was still putting out more than .5 VAC. Then I found some significant corrosion on the coil connectors. I cleaned them and put a little electric grease on them to keep them that way. This time the jeep ran for about one mile before it shut off. I was able to repeatedly crank it and have it run for 30 seconds at a time and got it back to the house.

The ICU was pretty cheap so I replaced it but I still have no spark. I have measured 12 v and a good ground coming in and making it to the coil. I have metered my coil and it meets all of the resistance requirements.

Next I am looking at the 5v square wave signal coming from the ECU. I have to wait till I go into work to get the oscilloscope so I can see the square wave. While I was waiting I wanted to find a pin out of the ECU and maybe a block diagram of how it works. I just want to make sure that I get the correct parts this time.

Anyone have any info to help me out or know of something I am missing?

 

Note from DJ
More Trivia

 

Exactly. He needs to address this first.

Here is an excerpt from the link below....

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff.

http://cruiser54.com/?p=19

 

Hope I'm not distracting again, pretty sure my TPS also grounds through the TCU.