TCM swap?

PAVINGMAN2001

MEMBER
2004 CHEVROLET SILVERADO
4.8L
V8
4WD
AUTOMATIC
230,557 MILES

My question is, can I use a TCM from a 5.7? It's the same year of truck and everything just different engine size same transmission and I have the ECM too. If I need to change it out, if I can, I figure I could swap the wire harnesses around and maybe it would work so any info would be greatly appreciated.

5 Replies

STEVE W.

MECHANIC
13,555 POSTS

While the part number of the base module may be the same the internal programming will be different due to the different engine size. So, you would need to have the module re-flashed to make it work properly. What is the reason for the swap?

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Tuesday, December 20th, 2022 AT 8:31 AM

PAVINGMAN2001

MEMBER
3 POSTS

Can I put it in there and then do a hard reset and let it relearn to the 4.8 motor? I'm just trying to save time and money that's all.

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Tuesday, December 20th, 2022 AT 8:36 AM

STEVE W.

MECHANIC
13,555 POSTS

Hard reset only clears learned memory it doesn't change the actual base programming which is different based on the engine and vehicle parameters. In this case the injector and spark programming would be different as would the shift points and pressures in the transmission at the least. If the gearing or even something like the ABS programming was different it would alter the ECM and TCM programming.
It wasn't as bad as the parts are now but even 20 years ago parts interchange was becoming a problem.

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Tuesday, December 20th, 2022 AT 5:43 PM

PAVINGMAN2001

MEMBER
3 POSTS

I appreciate your answer I kind of figured it wouldn't since they were two different engine sizes, I guess there's just some things you can't cut corners with LOL, but I found a remanufactured TCM so hopefully that solves my problem. Again, thanks for responding.

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Wednesday, December 21st, 2022 AT 5:07 AM

STEVE W.