PaulW

I just installed an LS2 with a 4L60E in my '36 Ford. Then engine runs fine but the Trans. won't shift. Starts out in 2nd gear and stays there. I can manually shift to 1st., but no 3rd or OD. My scanner recognizes both modules ('06 GTO), reads the engine ok but not the TCM. I have the correct range switch for the harness, and verified +12 volts on pin E at trans., and pin 31 at TCM. Don't know where to go from here. Any suggestions?

mrvedit

First, I suspect the trans starts in 3rd, which is the 4L60E "limp mode".
Is your scanner showing MPH? (The TCM needs an accurate speed signal.)
What scanner are you using? What ECM and TCM are you using?

PaulW

I had a friend use his high dollar Snap-on scan tool. The scanner will communicate with both the ECM and the TCM but neither one are "talking' to each other. Does the ECM and the TCM have to be "paired" if that's the right word? The CAN (GMLAN) bus is just a two wire loop. The ECM is an E40 and a TCM 42, Delco 24252114. The car drives the same with the TCM unplugged.

clinebarger

So you have U01XX (Communication) codes in both modules?

Is the ECM & TCM from the same vehicle?

PaulW

The U codes are in the TCM. The ECM appears to be OK. The ECM as near as I know came from the '05 or '06 GTO. The TCM came later, different source. I have to question the "address" of each module, and the fact that the TCM is putting out what seem to be default outputs.

clinebarger

Sounds like the ECM is out of a T56 car/Not compatible with the T42 TCM your using. I am not a Tuner by any means, And have reverted to buying matching ECM/TCM in the past when Tuners cannot figure it out...Or brick a PCM/TCM