transmission control module (TCM)

[wlhodgers]

what are some of the causes of the TCM to fail. on a 06 gmc sierra 3500 4x4 6.6
duramax diesel.

[More Power]

Make sure a battery cable or jumper cable isn't making contact with the metal case of the TCM. Any 12v short between the batteries and the metal cases of the TCM/ECM will cause that module to fail.

[Kennedy]

I'm quite shocked at how many do not know how to deal with dual battery electrical systems. I've had quite a few calls regarding ECM's that were arced out. when one battery was disconnected but not the other. The TCM has a thin sheet insulator over the hedgehog heat sink, but these can crack off. Also I have heard rumor of belt static especially dual alt trucks. It seems that GM added a plastic disc to the pulleys on some alternators likely related. I don't get a lot of calls on the TCM, but I do try to keep some good used ones on hand at all times.