96-98 PCM repair procedure W/Pictures - Page 7 - JeepForum.com

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post #91 of 208 Old 02-03-2013, 11:55 AM
SonsJeep
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Well results not so great. Got all the solder joints cleaned up, They look really nice now. Put is back together temporarily and started the jeep up. Fired up fine, Took it for a drive. About 5 minutes into my drive the ABS light comes on - then all the gauges drop - then go full scale. Car still running fine otherwise. Roll down driver window to smell for smoke (natural instinct) smell nothing, but window wont roll up. Roll down passenger side - It wont roll up. Try Driver side again it rolls up. still not passenger side. I get back home and connect a meter and I have 18v on the electrical system. Yikes! Put the module I bought from ACM in December (I am still having stalling problems even with their repaired module thus prompting my current attempt to repair the old one) Anyway I put that module in and the voltage is back to normal and all the gauges are back where they belong. And it still stalls. Passenger side window still wont roll up however.
I have looked all over the module for where I might have introduced a solder bridge and I dont see any. Any Ideas on this?

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post #92 of 208 Old 04-18-2013, 01:12 PM
rw-zj1996
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Quote:
Originally Posted by SonsJeep View Post
Well results not so great. Got all the solder joints cleaned up, They look really nice now. Put is back together temporarily and started the jeep up. Fired up fine, Took it for a drive. About 5 minutes into my drive the ABS light comes on - then all the gauges drop - then go full scale. Car still running fine otherwise. Roll down driver window to smell for smoke (natural instinct) smell nothing, but window wont roll up. Roll down passenger side - It wont roll up. Try Driver side again it rolls up. still not passenger side. I get back home and connect a meter and I have 18v on the electrical system. Yikes! Put the module I bought from ACM in December (I am still having stalling problems even with their repaired module thus prompting my current attempt to repair the old one) Anyway I put that module in and the voltage is back to normal and all the gauges are back where they belong. And it still stalls. Passenger side window still wont roll up however.
I have looked all over the module for where I might have introduced a solder bridge and I dont see any. Any Ideas on this?
That's pretty disturbing! It's good that everything still works after that. I read somewhere (either in the service manual or another forum post) that the computer determines how much voltage is being made, as in if you disconnect ECU black connector 1 while running or too soon after turning off the ignition, the computer will tell the voltage generation system to put out 0 volts and "the only fix is ECU replacement."

My best guess on that is there was some resistance on the loose connection for whatever circuit detects the voltage reference from the alternator, and re-soldering the board fixed that, causing the high voltage. I keep thinking about it, and that doesn't make much sense either. It could be something is just half fried.

If reprogramming back to factory settings would get it back to working order, that might be an option, but that's an extremely rough guess, as well.

If anyone happens upon this and has a better idea, I'm open to anything.
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post #93 of 208 Old 04-18-2013, 01:21 PM
rw-zj1996
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I'm lucky I happened upon this forum post! I've been having the same issues with my 96 JGC... the person I got it from was having trouble with stalling while slowing down to stops at traffic lights after driving for 10+ minutes... ECU solder connections were the last thing I would have suspected.

We bought a replacement computer from ACR in 2012 and had the exact same issues - so I figured it was SOMETHING ELSE. nope. One day I wiggled connector C (left side) and bam, stall. but it didn't always stall. You have to fiddle with it a lot, sometimes. Lovely, lovely intermittent issues. I foolishly sent the old computer back as a core for the warranty, because I could never find this thread, so have been unable to take apart the current one.

Currently have it zip-tied pulling outward slightly on connector C. (fortunately we have a spare connector)

We'll see if the place can fix it under warranty. I've been putting it off since that means being without a vehicle for a while. I'm really thankful I found this post. the pictures are extremely helpful (even if I don't have to do the fix, myself... this time)
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post #94 of 208 Old 05-19-2013, 05:38 AM
Pajkon
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Hello,

Will this fix works with that PCM (it's from 1996 5.2 Orvis)?:



The problem - there is no "top cover". Cover is "u-shape" :/
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post #95 of 208 Old 05-19-2013, 09:01 PM
SonsJeep
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I bought a replacement from ACM as well, had to send it back and get another one which took considerable pushing from my end. They were reluctant to do that. But the second module worked and has been fine since.
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post #96 of 208 Old 06-08-2013, 04:01 PM
sillygoose
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First off, thanks for this write up. I have got nearly all of the potting material off but still want to clean it up more. However, I am not seeing any noticeable broken solder joints on any of the pins. Does this mean that the connections are fine? When troubleshooting, I found that the center plug seemed to be where the culprit was, but I am not finding anything that looks like a broken connection. Should I re-solder them anyways?
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post #97 of 208 Old 06-08-2013, 05:34 PM
SonsJeep
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You might have to look really hard, it may just look like a dark ring. And the cracks might be on the other side of the board. If it were me I would reflow them again, even though I somehow killed mine the first time. Even the pro rebuilders don't get them all fixed. You dont have much to lose.
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post #98 of 208 Old 06-11-2013, 04:27 PM
sillygoose
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Just an update. I reflowed all of the center pins (which was the suspected plug) and have drove it the past two days. So far so good. As I said, there was no visible flaws, but hopefully this did fix it. Either way, thanks again for the write up! Now, hopefully I can go on trips without stressing about whether or not my jeep is going to start back up again!
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post #99 of 208 Old 06-11-2013, 08:40 PM
SonsJeep
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Give it a couple days before you celebrate, but congratulations. You should resist the temptation to go back in and touch up the rest of the pins if it runs OK. Risk of damaging a successful repair is looming if you tempt fate.
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post #100 of 208 Old 07-19-2013, 09:59 PM
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I've been having stalling problems for the past year. It's been progressively getting worse to the point now that it just stalled all the time and was undrivable. I wiggle the wires and I could get it to stall or sputter on for a little more.

Since I solder for a living, trying to fix it is right up my alley. Pulled it apart as per the instructions at the beginning of this thread. I reflowed and added more solder to all the connectors and some other parts that looked a little light to me.
I then replaced the three electrolytic capacitors. Put it back together and cleaned all the connectors with contact cleaner and put some dielectric grease to in the connector sockets and around each connector to make a more environmental tight seal. Three days now and it's been running perfect!
The three caps in mine were two 220F and one 470F electrolytic.
I replaced them with the same exact parts from Digikey.
Part #'s
493-1864-ND
493-4503-1-ND

So for about $4 ($2 for dielectric grease) I seemed to have fixed what the Jeep dealership and a handful of other garages couldn't. Thanks for this how to thread. Fingers crossed it holds up.

-Bill
--------------------------------------------------------------------
1998 Red Grand Cherokee Laredo
6" Lift - 32 x 11.5 BFG MT's - K&N FIPK - MSD Ignition with Magnecore wires - JKS Control Arms, Trackbars and QD's - Addco Front Swaybar - Intake Swap - U-turn Steering Conversion
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post #101 of 208 Old 07-20-2013, 05:53 AM
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What led you to the caps, did they look bad?

Info on projects and repairs categorized by system
http://www.jeepforum.com/forum/f13/c...-faqs-2863665/

Originally Posted by HighLonesome
lol...if life is as a simple as a 5.9 making you happy, I'd say go ahead and buy it on impulse. ZJs are the way of Zen. Wax on, wax off
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post #102 of 208 Old 07-20-2013, 05:58 AM Thread Starter
JS97ZJ
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I'm going into my 2nd year since the write up and hasn't faltered since.

Good luck.

P.S. If it does come back, take a look at Zee's 12 Things write. This has helped countless others.

http://www.jeepforum.com/forum/f13/1...talls-1407423/
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post #103 of 208 Old 07-20-2013, 08:09 AM
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Quote:
Originally Posted by coralman View Post
What led you to the caps, did they look bad?
No. They weren't bulging or anything. I just wanted to do everything I could to it while I had it open. It's easy stuff for me since I do stuff like this everyday. The hardest and most time consuming part was dealing with the harder/thicker potting stuff. Most of the soft gel/potting stuff was messed up when I separated it so I removed it all and reflowed all of those parts and added a little solder to ones I thought were light. The gel went back in pretty decent.
I still have the old caps. I could probably test them to see if they are bad but it really doesn't matter.

@JS97ZJ: I did read through that. It's a very useful read. I actually decided to replace all my battery cables because if it. I can't really tighten my negative terminal down too well because it's cracked and originally I thought that was the problem. I thought it was coming loose and stalling but it wasn't. I ordered the parts I needed yesterday. I'm going with military terminals and 1/0 gauge wire. I found some cool solder-on cable ends I'm going to try out.

-Bill
--------------------------------------------------------------------
1998 Red Grand Cherokee Laredo
6" Lift - 32 x 11.5 BFG MT's - K&N FIPK - MSD Ignition with Magnecore wires - JKS Control Arms, Trackbars and QD's - Addco Front Swaybar - Intake Swap - U-turn Steering Conversion
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post #104 of 208 Old 07-26-2013, 08:41 AM
dylantheheeler
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Did this repair to a cardone reman that was out of warranty. Worked like a charm. Now just to give it a few weeks...
Thank you very much for this write up!


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post #105 of 208 Old 07-26-2013, 10:33 AM Thread Starter
JS97ZJ
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Glad it helped>

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