Renix ECU removal
04-29-2017 | 06:57 PM
#31
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
04-30-2017 | 12:13 PM
#32
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Correct. Don't expect you would remember, but my old Brown 90's TCU has a fault and is not grounding the TPS. Adjusted to it's own ground it shifts perfect. My new White 90, it's TCU grounds the TPS fine, but I'm chasing a rare, intermittent, hot, no up-shift problem!
Point is one Renix owner reports his shifts fine with the trans side of the TPS ground to the TCU, fubar. (and there IS a ground from the tps through the TCU)
Nice pic of the dipstick stud btw
Point is one Renix owner reports his shifts fine with the trans side of the TPS ground to the TCU, fubar. (and there IS a ground from the tps through the TCU)
Nice pic of the dipstick stud btw
Last edited by DFlintstone; 04-30-2017 at 12:13 PM. Reason: fine
05-01-2017 | 01:28 PM
#33
Thread Starter
Newbie
Joined: Dec 2012
Posts: 14
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Model: Cherokee
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?
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?
First,I have received emails that this thread has been kept alive. I think that's very helpful, compliments to the moderator.
To Cjjal:
Not sure if I can add to what you have already done. I went through all that has been mentioned: TCU, coil, ground connections under dip stick & any place else I could find. My fix was the ICM/ICU (and mine wasn't cheap-$100). To be clear, my 'somewhat helpful' Haynes manual calls it Ignition Control Module while most here say Ignition Control Unit. I hope we're all on the same page: that THING under the coil. Anyway, haven't had a no start problem since I replaced it.
You say there is 12v into the coil. My manual says that even if the coil ohms out ok it could still be bad. I had already replaced mine so that was a non-issue but something to think about. If you can determine coil output then maybe something inside the distributor.
Hope that helps,
Steve in Oregon
05-01-2017 | 08:48 PM
#34
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
2, There was a band on N.Bank just west of Hioucchi bridge, met a guy Dave is still there.
Forum, here I had some success seeing the signal from the Puter' to the coil module on a Renix. I might suspect the coil side if I saw that signal. Pretty short >
Forum, here I had some success seeing the signal from the Puter' to the coil module on a Renix. I might suspect the coil side if I saw that signal. Pretty short >
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