LML Tcm

ikeG

Oughta Know Better
Apr 19, 2011
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Does heat soak bring on the dreaded bad tcm issues? I have one here that will drive fine until you stop and let it idle. Trips a dozen dtcs. Voltsge, over temp, etc

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2004LB7

Well-known member
Dec 15, 2010
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Norcal
I've never heard of it on a Duramax. But plenty of times for other electronics. Usually caused by a cracked solder joint. Only way to fix it short of replacement, is to reflow the solder. Happens most often at the chips or the connectors.

The 1st generation X boxes had this issue. Fixed one for my cousin by fluxing the chips and putting it in the oven to melt the solder.
 

Dallas S

Active member
Jun 17, 2009
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Alberta
I have a “test” T14 here that fails every time internal temp hits 76? 67? Degrees. There is a PID for TCM temp. Our “test” unit always works cold, and when it hits that certain internal temp it appears to go into a relearn mode(increased rpm, random clutch application)
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Phoenix Az
IIRC the overheat is something to do with lack of heat transfer from the chip to the heatsink, could be a cold joint too. Evan had a truck come in while i was at his shop that did the same shit. Kory said "put it in the freezer for a bit, probably works fine after you put it back in". sure as shit, it did.
 

ikeG

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Apr 19, 2011
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The one I have here now fails at 116 degrees everytime. So in this cold weather, it never gets that warm until you stop. Then it slowly heats up.

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ikeG

Oughta Know Better
Apr 19, 2011
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Western PA
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The one I have here now fails at 116 degrees everytime. So in this cold weather, it never gets that warm until you stop. Then it slowly heats up.

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ParisWash

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Nov 23, 2021
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Any update on this issue? I have a new replacement from GM with less than 200 miles on it and I have a feeling it overheated itself just now. It’s cooked a few transmissions and I would love to find an answer.