Where is the TCM located?

CHRIS WADE

MEMBER
2006 CHEVROLET SILVERADO
5.3L
V8
2WD
AUTOMATIC
254,000 MILES

I'm trying to locate the TCM for my truck listed above. One day out of nowhere while driving my truck decided it didn't want to shift out of 3rd gear. Also, just to get the truck going I had to engage the tow mode once it hits 40 MPH. I have to disengage the tow mode, or the transmission won't catch and at that point I can only go about 45 mph or if I'm hitting 50 it's tacking at 3000 RPMs and hard shifting is definitely present. I have replaced two of the shift solutions in the transmission pan new filter and fluid and have been doing a lot of research and determined that the ECM, the TCM, and the BCM could all be part of the issue as well as mechanical issues inside the transmission so here I am still trying to figure it out and now I am trying to locate the TCM and determine if the new TCM has to be programmed or what is the correct process of installation.

Saturday, January 4th, 2025 AT 7:00 AM

2 Replies

AL514

MECHANIC
5,499 POSTS

Hello, with these different problems, have you had the entire vehicle scanned for diagnostic trouble codes? The must be codes setting in either the PCM or TCM. And I don't mean just scanning the PCM with a basic OBD2 scan tool, you need a full system scan done. The TCM does need to programmed, if replaced, that requires a capable scan tool as well. But I would check for codes first and go from there. If there's an issue with the vehicles network and there is a communications issue between the PCM and TCM, you could have these types of issues as well. I'll post the service info on programming the TCM, but you don't want to replace that module and still have the same issues.

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Sunday, January 5th, 2025 AT 9:35 AM

AL514

MECHANIC
5,499 POSTS

Diagrams 1 and 2 are for a transmission line test, which is something you should do to rule out a pressure issue with the pump inside the transmission, diagram 3 is the wiring harness to the transmission itself, diagram 4 is the TCM location and 5 is the module programming. But let us know what codes are stored in any modules first, that way we can look up the testing procedure for any specific codes.
Corrosion in any of the connectors will also cause faults like this, being a 2006 and if you live in an area where they use salt on the roads during the winter, you could definitely have connector issues or if connectors have been disconnected and reconnected a bunch of times, there could be pin fitment issues.

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