96-98 PCM repair procedure W/Pictures - Page 5 - JeepForum.com

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post #61 of 208 Old 06-02-2012, 11:02 PM
ZeeJay1997
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Quote:
Originally Posted by JS97ZJ View Post
I had always thought that these snake like sections of print on circuit boards were protection areas similar to inline fuses.
I am inclined to agree w/you.



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post #62 of 208 Old 06-03-2012, 12:19 AM Thread Starter
JS97ZJ
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Quote:
Originally Posted by ZeeJay1997 View Post
I am inclined to agree w/you.
Well, I''m still learning.
I checked with the electronics forum that I cruise for info, and that section of circuit board is known as a "smoke n char" protection area. If we only had the schematic

This inline fuse blew out either due to an outside short (sensor?) or an internal fault. I don't have my spare PCM cleaned off enough to try making a guess at what is wrong with his unit.
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post #63 of 208 Old 06-03-2012, 04:17 AM
coralman
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Yep. its frustrating to see something figured out to a point and dead ended because Chrysler wants to protect a antique unit by denial of knowledge.
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post #64 of 208 Old 06-03-2012, 07:28 AM Thread Starter
JS97ZJ
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[QUOTE=framanda;13659598]My jeep has been stalling cutting out and having an intermittent miss for a few months now so i figured i would tear into the pcm and cure the problem. Well when i got in there i found this, you could see a dark patch under the potting compound and when i started peeling it away it was fried, the piece of wire came up with the potting compound. Any ideas what would cause this? for reference its the s shaped wire on the right in the bottom pic.


This inline fuse seems to be located on the same side as the 5v power supply regulator. Since the engine was running before you dissasembled the PCM, it must not have been cooked all the way though. When you removed the potting compound you probably pulled the rest of the print off the board.

If I were you I'd do a simple check for frayed wires on the O2, crank and cam sensors, then check possible other engine sensor related wiring problems. Plug the connectors back into the PCM (w/o putting it into the case) and check for 5v at the point on the bottom of your picture to ground.
If you have the 5 volts, and the wiring checks out, solder a jumper in there, and take it for a short ride.

If it seems ok, go on with the reflow of the pins. That's the best I can come up with, other than replacing the PCM.

The damage to the inline fuse might have occurred due to a surge at one point in the passed that didn't totally blow it. I'm sure that in the state it's in now it's not going to work at all.

At any rate, if you go for a (new) PCM, I'd be sure to check your wiring and sensors anyway.
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post #65 of 208 Old 06-08-2012, 12:11 PM
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2007 WK Grand Cherokee PCM problems

[quote=JS97ZJ;13664036]
Quote:
Originally Posted by framanda View Post
My jeep has been stalling cutting out and having an intermittent miss for a few months now so i figured i would tear into the pcm and cure the problem. Well when i got in there i found this, you could see a dark patch under the potting compound and when i started peeling it away it was fried, the piece of wire came up with the potting compound. Any ideas what would cause this? for reference its the s shaped wire on the right in the bottom pic.


This inline fuse seems to be located on the same side as the 5v power supply regulator. Since the engine was running before you dissasembled the PCM, it must not have been cooked all the way though. When you removed the potting compound you probably pulled the rest of the print off the board.

If I were you I'd do a simple check for frayed wires on the O2, crank and cam sensors, then check possible other engine sensor related wiring problems. Plug the connectors back into the PCM (w/o putting it into the case) and check for 5v at the point on the bottom of your picture to ground.
If you have the 5 volts, and the wiring checks out, solder a jumper in there, and take it for a short ride.



If it seems ok, go on with the reflow of the pins. That's the best I can come up with, other than replacing the PCM.

The damage to the inline fuse might have occurred due to a surge at one point in the passed that didn't totally blow it. I'm sure that in the state it's in now it's not going to work at all.

At any rate, if you go for a (new) PCM, I'd be sure to check your wiring and sensors anyway.

Thanks all you guys for all the work gone into this solution. I wish it would work or my 07 WK 6.1 Hemi, but the PCM construction is totally different. When I get to my laptop I will upload the images of the inside, but there is no compound or gel inside, the two halves of the casing are almost welded together by a liquid silicon gasket material and the male connector housing for the MB is connected through the top casing half, where it is held on by 6 Torx screws, and the connection pins are then soldered through to the component side of the MB. In order to be able to reflow all the connections all 114 pins of the connector housing would have to be desoldered so that the housing could be removed.
Only then would it be possible to get access to the printed circuit side to reflow the solder. What a work up.
With the help of my son I did rig up just the MB outside of the case, with a jury-rigged ground to the body and got the car started, albeit a bit rough.
I then tapped the board itself with the rubber covered handle of a pair of side cutters.
It did not die when I tapped the soldered joints of the connectors to the MB but when I tapped the corner near what looks like a chip with a clear plastic cover, it died.
The solder on this is accessible and so I am gonna have a crack a this tomorrow.
It couldnot get any worse, right!
If anybody has any good ideas on how to get to the backside and reflow, would love to hear them.
Would also like to know of any forum tried and recommended shops who supply refurbs or who do refurb of PCM's an ship overseas.

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post #66 of 208 Old 06-09-2012, 11:50 PM Thread Starter
JS97ZJ
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Pictures?
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post #67 of 208 Old 06-10-2012, 12:02 AM
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Quote:
Originally Posted by JS97ZJ
Pictures?
I need to get to my laptop to be able to send the pictures as the I-Pad won't let me attach them. Otherwise, I need an e-mail address to send the photo direct for the album in my I-Pad.

I will try to get them off today as been busy with being Mr Fix-It for son, daughter and all.

Archie
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post #68 of 208 Old 06-12-2012, 06:23 AM
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96-98 PCm versus 2006 PCM failure

Quote:
Originally Posted by JS97ZJ View Post
Pictures?
Bit later than I expected but here are the pics of the PCM in the SRT8. Tried resoldering all the joints but runs worse now and won't idle at all, with extrem rich running.
Suspect the small red IC in the lower right corner as when tap it, car dies. Also the blue covered coil with a damaged cover - it never fell out when I finally got it open - looks suspect.

Any thoughts
Attached Thumbnails
PCM Photo 2.jpg   PCM Photo 1.jpg  
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post #69 of 208 Old 06-12-2012, 01:54 PM Thread Starter
JS97ZJ
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Hi Rogue,

I just got through reading a thread that has been going on for a couple of years over in the WJ section, and it seems that the Hemi's are plagued with the same problem.

I cant see by your pictures how to best tackle that board removal, but after reading the WJ thread it would make sense to me that your on the right track.

There is a lot of screws on both sides of that CB. I'd get a very good magnifying glass and check for cracks in the board. Jeep had a recall one year (I forget which) that the changes in temp was causing the potting compound to expand and contract so much that it was cracking the CB.

After that it's a judgement call on your part as to the best way to get it out. Is there potting compound holding it in, if all the screws are removed? it looks like they took extra time out to make sure it couldn't be taken apart. But that wouldn't stop me.

He's the link to the WJ site were that actively pursuing this problem.

http://www.jeepforum.com/forum/f67/2...oblem-1147825/
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post #70 of 208 Old 06-12-2012, 02:17 PM
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Hi ZJ,

Thanks for the feedback.

There is no potting compound in the module. When you look at the board, it is directly on the flat top cover ( the one in the other picture showing the connectors and the serial/part numbers. Don't know if it is attached to the flat plate by some kind of silicon adhesive.

Regarding the screws, I am with you, but looking at it, it seems that the screws are intended to position the connector block onto the aluminium cover plate and then the circuit board is laid over the connector pins protruding through to the inner side of the cover plate and which are then soldered in.

I can remove the screws but I am guessing that I would have to desolder all of the 114 pins from the black, orange and white connectors in order to be able to remove it and then the circuit board.

I will take your good advice though and get a good magnifying glass to check the board for cracks and the joints - which I have now resoldered twice - for any signs of weakness.


Will come back on this. What is worse is the previous Owner has removed the tow hooks from front and rear so to get it on a recovery truck without ripping of the very low front fender is going to be a nightmare

:-(

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post #71 of 208 Old 06-13-2012, 11:20 AM Thread Starter
JS97ZJ
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Quote:
Originally Posted by desert_rogue View Post
Suspect the small red IC in the lower right corner as when tap it, car dies. Also the blue covered coil with a damaged cover - it never fell out when I finally got it open - looks suspect.

Any thoughts
Over the last couple of weeks, I've had to replace a couple of diodes. One was in a septic alarm system and another in a computer power supply. Both diodes were intermittent. I've repaired all kinds of electronic stuff over the years, but have never seen intermittent diodes. In reading through different electronic forums, the consensus is, that many parts that are made in China (not Japan) have been inferior to the American made brands. US armed forces refuse to use parts made in China just for that reason. But many American companies will have there products made in China regardless of the quality that we've become used to seeing in the products that we buy.

They shouldn't skimp when it comes to safety. I don't drive a toaster. I drive a 5000 lb. missile. KEEP IT IN AMERICA!!

The underside of that board will most likely only have print (tracings). So there's probably nothing to do under there anyway.

The red chip should have a number on it and can be google'd for a replacement. These chips can usually be replace for about $5-10. Coils probably less. The problem is the stuff that is made by Chinese manufacturers print production line numbers on some of these components that can't be referenced to a replacement part. A schematic is needed. Good luck there! The Japanese made parts usually print part numbers. And the US made....always.

If the chip is going wacky when it's very lightly tapped, you can apply heat from a soldering iron to the surface of the chip for no more than 2 seconds. This will expand the silicone within the chip, causing it to either make better contact and start functioning properly or cause the symptoms to get worse.
These chips are manufactured with a temperature durability range for the amount of heat they can take, and for how long they can stand that heat, for the purpose of manufacturing the circuit boards. It's a technician's trick.

I think if there is a problem on that board, it's probably starring you in the face. Recheck you solder connections with a good magnifying glass. It isn't hard to cause a short between pins and the small print on that board. happened to me more than once.
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post #72 of 208 Old 06-13-2012, 12:21 PM
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X2 on american made, and I think in some areas everyday people are snapping to the fact that cheaper isn't always the course to follow. Just to tell you JS,I broke open that abs controller and sure enough one of the motor power pins had absolutely no solder left on it. Haven't had time to resolder but I will get to it eventually.
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post #73 of 208 Old 06-13-2012, 01:52 PM
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I went and got a good glass today and will check it over. I googled the TDK number on the "suspect" red chip, which actually looks like some kind of coil, and it through me to a site of an electronics component dealer in Russia.
Who knows where all the parts on this board came from.

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post #74 of 208 Old 06-15-2012, 09:26 AM Thread Starter
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TDK was always an American company that has made excellent parts. I don't think they out source. As for it being a coil, the site you googled was just a bad search.....it should have looked like this,

http://www.tdk.com/product-portal.php
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post #75 of 208 Old 07-12-2012, 10:24 PM
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Looks like I need to do this again after 7 months problem free it decided to come back with a vengeance. Somewhere I probably fudged up, I'll open it tommorow to see.

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Originally Posted by BlackDaddyZJ View Post
in all of that i dont hear no, which by my logic and calculations actually means yes:2thumbsup:
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