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Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > TCM capacitor replacment

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Unread 09-19-2013, 07:40 PM   #1
zjosh93
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TCM capacitor replacment

I've already had to replace the capacitors in the PCM of my 93. I've also had to replace a bad capacitor in my VIC. I had a spare and a broken TCM so I thought I'd check to see if there were any (possibly bad) capacitors inside. There's only one. After I replaced it my shifting has improved noticeably. I had previously adjusted the kickdown cable shorter so it would shift better. Now I've adjusted the cable back and it shifts even better than before.

I did this on my 93 4.0 with the 42RE and one of the TCMs is a 94 so I think this will work for the 93-95 42RE TCMs. Not sure if the V8s have a TCm and I'm pretty sure the later models combine the TCM into the PCM. Anyway, here's how you do it:


Here's the TCM.


Use pliers to carefully bend the tabs up.


Here's the inside of the TCM. Just one big capacitor to replace. The one you want is a 470 microfarads at 35 volts, or at least all three of mine were.


One screw to get the board free of the case.

I'm not going to go into detail on the actual soldering because it's pretty well covered in other posts and on youtube. Also it takes two hands and I can't take a picture and solder at the same time. I will say that a solder sucker and solder wick help a lot. The white stripe needs to point the same way when you install the new one as the old one. I tested all three of the one's I have and all three old capacitors were bad.


Clip the tails down so they don't short out on the case.


The finished solder joints.


One new capacitor installed and ready to go. No nasty potting compound here!


On the TCM that actually went bad this relay was the culprit. Notice the burned pin. I couldn't find a replacement and junkyard TCMs are cheap enough.

Hope this helps someone. I also went around and reflowed most of the through mount solder pins just to be sure since Jeep seems to have issues with cracked solder joints.

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Unread 09-19-2013, 07:50 PM   #2
ZeeJay1997
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Good work. I think you broke new ground.

Look like the cap was bulged a little. For those that don't know, the X on top it where to look for the bulge.
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Unread 09-20-2013, 05:48 AM   #3
coralman
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I agree,good post! A cap is a cap is a cap. On residential A/C systems, 9 out of ten, if they go bad they swell on top.
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Unread 09-21-2013, 12:54 AM   #4
zjosh93
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Here is a link to the capacitor I used:
http://www.digikey.com/product-searc...=0&pageSize=25

This is the data sheet for the burned relay:
http://www.sourceresearch.com/potter...ge=t70_dsw.pdf
Unfortunately I couldn't find the exact same relay for sale. It's a Potter & Brumfield part number T70L5D164-5.

I matched the specs up to this Omron relay:
http://www.digikey.com/product-detai...DC5-ND/1815599
I've ordered one so I'll solder it in and see if it works when it gets in.
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Unread 09-21-2013, 06:41 AM   #5
coralman
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Even though trans control is incorporated in the pcm in mine, I enjoy the ingenuity of projects like yours Josh. Good thread!
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Unread 09-21-2013, 09:42 AM   #6
ZeeJay1997
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Quote:
Originally Posted by zjosh93 View Post
I've ordered one so I'll solder it in and see if it works when it gets in.
The only thing i see that could be a problem is the coil voltage and that's only because i dont know the board voltages of the TCM. If you have all that figured out, the relay should do fine.

As long as it's the same coil voltage and amp rating, the rest of it can be dealt with. That's what they make hot glue, heat shrink, duct tape, bailing wire for.
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Unread 09-21-2013, 08:31 PM   #7
zjosh93
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Thanks guys! This is the kind of stuff I used to love to do when I sold parts, tracking down oddball or rare hard-to-find parts. I now have three TCMs to play with so I can experiment a little.

Besides, I was this -><- close to buying a junkyard trans when I found a post here that pointed to a possible bad TCM. I ended up getting a JY TCM for $35 and fixing my problem instead of $350 for a JY trans and not fixing anything.
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Unread 09-21-2013, 08:50 PM   #8
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Good thread, I love to see people getting into the guts of stuff like this so we electrical laymen can follow along.
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Unread 09-21-2013, 10:07 PM   #9
newfieZJ
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Interesting stuff Josh . This is why I come on JF , every problem has a solution and your gonna find that fix on here . Nice find !!
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Unread 09-28-2013, 04:46 PM   #10
zjosh93
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Update. Got the new relay in and double checked the specs to make sure it was a match; soldered the new relay and a new capacitor in my original broken TCM; reflowed any pin that went through the board; and visually checked all the solder joints with a 10X magnifying lens. This TCM was putting the trans in limp mode and giving me codes for the governor solenoid and sensor even after I replaced them. With the new capacitor and relay it shifts fine, no codes, no limp mode. The repair cost a total of $4. Much better than the $202 for a rebuilt one on rockauto.
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Unread 09-28-2013, 07:17 PM   #11
ZeeJay1997
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one in the W column for josh.
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Unread 12-18-2013, 11:31 AM   #12
VTOLRN
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Thank you for this. I'm going to tear into mine in a minute
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Unread 12-18-2013, 05:13 PM   #13
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Excellent post! This is what I like to find on here! Enginuity at it's highest
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