Hey I am working on my harness and I came across this diagram for the GMLAN high speed. My question is do I need to run the lines that go from the DLC to BCM to the EBCM and back to the TCM? It looks like to me without those there is not communication between the DLC and the TCM. The car is a 2010 Express. Do I actually need the GMLAN lines for the swap?

 

You should be able to put the TCM onto the bus directly without passing through the EBCM/BCM if that is what you are trying to do. The ECM and TCM do communicate via the bus, so they will have to be able to talk to each other.

 

okay. Cool that is what I was thinking, but was not sure. Do I just take it from the JX250 A/M directly to TCM 38/37?

 

It should work. We tie into CAN stuff all the time here at work, and that is how we do it. A lot of vehicles today will have a CAN bus "filter" module on the OBD-II diagnostic port, so we tie equipment in elsewhere throughout the vehicle, like the steering wheel angle sensor, etc... It all works fine.

I can't promise you it will work, but it should. Check a few others responses here as well if they chime in.