Hi everyone...Im looking at all the GM tech documents for differences between the 5-speed Ally and 6-speed Ally and their respective TCM's, valve bodies, etc. I know, I know it probably wont work, but hey I can dream!:rolleyes: And it doesnt hurt to look into it. Question tho for one of the techs who is familiar with the data-busses and such.

On the 5-speed Ally I see pins and wires for "CAN data" going from the PCM to the TCM

On the 6-speed Ally I see pins and wires for "GMLAN data" going from the PCM to the TCM/

Are these two data busses the same? I know GMLAN is based on the CAN (controller area network) so they are interchangable, correct? Meaning if you hooked the wire for the 2006 TCM that says "GMLAN" to the 2003-2005 LLY's "CAN bus" wire, they would talk to eachother, right??? They cant be different because the 2006 8.1 liter trucks didnt get any PCM change to talk to the new Allison TCM, right??

Someone please :help: !!!

Thanks----Ben

GM LAN and CAN are not the same. They share some stuff but not all. I guess the best way to describe it would be to say we speak English (can) and they speak English and Spanish (gm LAN).

So if we hooked a GMLAN-speaking TCM to our 2003-2005 CAN-speaking PCM/ECM...would they talk to eachother and work??? I know thats a million dollar question...

---ben

My guess would be no, but you never know it might work.

I posted in the other thread, but I think it got deleted by one of the bots... Also in the Transmission thread

The 2006 TCM has "GMLAN" high speed connections for the 8.1L and the 6.6L. On the 8.1, two GMLAN + terminals get spliced together, and then you have the GMLAN -. For the Diesel, you have 4 connectors. one pair goes to the ECM, the other pair goes to the Glow Plug Controller. It's been said that the 2003-2006 8.1L uses the same communication protocol as the 2003-2005 Duramax. If this is the case, would it be possible to hook the new TCM into a 2003-2005 system using the connections for the 8.1L?

And the 2003-2005 trucks don't exactly use CAN (I don't think they do). I think they use J1939, a CAN variant. maybe early GMLAN.

I think the easy part of getting a 6 speed in a pre 2006 truck is the transmission. The hard part is integrating the electronics.

Do most of the controllers (such as the ABS module) communicate over the Class 2 bus? It was also said that the ABS controller and other controllers where unchanged for MY06. If that's the case, there must be something common between the 03-05 and the 06 ECM and TCM. If it's not Class 2, then.....

Thats what I'm thinking...

--Ben