casias

iTrader: (1)

I purchased a wiring harness from BP Automotive that was a brand new custom harness.

Initially, the harness did not have switched power to pin 47 on connector 1, so the ECM wouldn't wake up. The harness is already installed, and is not easy to remove. So I fished a wire from switched power and connected it to the pink wire in the connector, and the engine now starts and runs.

But we couldn't communicate with the TCM. I was told the 2007 TCM would not work with the 2010 ECM, so I replaced the TCM with a new 2010 TCM. Still can't communicate with it. I am assuming the TCM is not seeing switched power either.

Where should the TCM get it's switched power from? Can I hook it up to the same switched power the ECM is now connected to, or does it have to come for the ECM sensor relay?

Thanks

daveS

It shouldn't matter where switched power comes from, but it might be wise to add a small 10A inline fuse to the supply wire.

My connect and cruise package has a dedicated wire that comes from the GM supplied fuse box to power the TCM. The TCM harness includes a 10A inline fuse.

jcvett56

Regardless of what year the TCM is it will always communicate. It just may not run properly. You can grab an ignition source from where ever is convenient. However, before jumping into diagnosing more of the harness manufactures potential mistakes I would call and ask them for their pinout so you can verify what is or isn't missing. There should be a battery, igntition, and ground wire all in the 6L80 connector. BP should be able to give you the pinout.

casias

iTrader: (1)

So far, his service has been garbage since I have harness in hand. After the first problem with the ECM, my tuner tried to talk to him about the problems we are having with the TCM. He was very unhelpful.

Since I posted this, we have checked all of the pins on the trans connector. Pins 1 and 4 have constant power, and pins 2 and 5 have ground (as they should). Pin 12 has start/run switched power, as it should. Pins 10 and 11 were connected to 27 and 28 on the ECM, and pins 13 and 14 were connected to the DLC pins 6 and 14. These are switched, according to the wiring diagram we had, so we switched them after a couple hours of frustration, and that didn't solve it.

Pin 9 on the transmission connector is listed as accessory wakeup serial data, but doesn't have a pin/wire at all, so we applied 12v power to this with switched ignition, and this did not do anything for it.

We had 120 ohm across 6 and 14 on the DLC, and I had read somewhere we needed a terminating resistor at the DLC, and should have 60 ohms. So we added a 120 ohm resistor across 6 and 14, and saw 60 ohms. This didn't help either.

Then we tried a write entire file from hptuners using a 2010 camaro files ECM/TCM. It wrote the ECM file, but timed out at the TCM file.

Not sure where to go next, but BP is not going to help, so now I am pretty much on my own to figure this out.