2002 TCCM "Not Communicating"

[chase400]

Hi, and thanks in advance for helping a newbie and reading what is about to be a long winded first post.

I have a 2002 TB that has shown all the signs of a bad TCCM. The service light was on, switch lights flashed only momentarily on startup before going out completely, and the whole system is non-operational. Fuse 8 in the front and 48 in the back are both good.

I bought a "new" (as described by seller and as near as I can tell, it is) GM TCCM online (part #12509220) and installed it. That turned the service light off, but it also made the switch lights stop working all together - no blink on startup. When I went to the dealer to have it programmed, they said they couldn't communicate with the TCCM. I then paid for over an hours worth of diagnostics ($180) for them to tell me that fuse 8 was blown, but that they still couldn't communicate with it once it had been replaced. Diagnosis: bad TCCM. I'm not sure what to believe at this point since I had checked #8 before I took it in and it wasn't blown. I took the car home and now things get interesting.

I was going to try to return the "new" TCCM to get my money back, but when I put the original back in, absolutely nothing changed. The service light is still off and the switch lights are totally dead. WTF?

I don't see any corrosion on the terminal pins and the dealer said they didn't find any short circuits.

Any ideas before I waste more money?

Oh, and yes, I did visit that "other site" first, but found the error in my ways before I made a post!

 

[The_Roadie]

If only you had a local buddy to swap with first, that would be a better diagnostic than what you got at the dealer. Did they offer a refund in case you got a verified used one and *it* didn't work?

A totally new TCCM does indeed need programming at the dealer. That's why used and verified ones are actually worth more to the DIYer.

Do you have a meter and want to get into detailed troubleshooting using the schematics? Castro Valley is a bit far to drive down here, but there must be other members in your area to offer a TCCM test.

 

[chase400]

If I knew someone with this truck that would let me play with it, that definitely would have been my first move. I do have a meter, but not too sure where to start on diagnosing.

 

[chase400]

If I can't verify with someone else's unit, should I try one of the Dorman units (part # 599-113)? These come with a warranty and say they don't need any programming. Of course the downside is that I could end up spending another $170 with no guarantees. Thoughts?

 

[The_Roadie]

I wasn't aware Dorman was making replacements now. You could be the first to try one out and report on it.