No ecm tcm or gpcm

[technodude000]

Hey so been at this awhile. The gmlan bus is fine and if I unplug the tcm and jump the gmlan bus the whole system comes online. But as soon as I put the tcm back in can't see tcm pcm or ecm. Tried unplugging trans. Has all required powers and grounds. Any ideas I'm at a brick wall

 

[Chevy1925]

Need to make model year and what code you have but if you’re losing all GMlan with the TCM plugged in, but it comes back after you unplug the TCM and jump the wires, indicates the TCM has an internal problem

 

[technodude000]

Need to make model year and what code you have but if you’re losing all GMlan with the TCM plugged in, but it comes back after you unplug the TCM and jump the wires, indicates the TCM has an internal problem

Even with a brand new one
2012 2500hd with 6.6 duramax

 

[Chevy1925]

What’s the ohm reading on the + and - of the canbus line measured at the OBD2 port with the tcm hooked up?

 

[1FastBrick]

Was the New one Programed?

 

[TheBac]

Moved to LML section.

 

[technodude000]

So new development. Hooked just the tcm powers and cam bus wires up and can see everything but tcm still can't be seen. But that's only like this

 

[technodude000]

Should be able to be seen at this point and would throw every circuit code but still nothing

 

[Ron Nielson]

I don't think you will see the TCM with a scanner if the CANBUS connection at the TCM has been wired around.

 

[technodude000]

I don't think you will see the TCM with a scanner if the CANBUS connection at the TCM has been wired around.

It was wired through the tcm.

 

[Ron Nielson]

So if TCM is connected thru CANBUS but your scanner cannot communicate with it, it has power and ground, then I am with James on post #2.