No crank 6L80 TCM question

[Phestezio]

Trying to get my project running. Its a sprinter van with a 5.3 swap out of a 2011 silverado. I used everything out of the donor truck and removed any wires I didn't need, mostly from the interior harness. Only thing I removed from the engine harness was the purge valve, VVT and DOD since I rebuilt the engine and put a cam in. I also removed the FSCM and its related sensors and ran a fuel pump relay and mechanical regulator. Was alot easier to run the fuel this way with the sprinter tank. I moved the terminating resistor for the CAN bus from the FSCM connector to the ABS connector to keep the CAN bus intact. I did get a Jasper reman 6L80 and I know the TCM needs to be programmed still.

I went to try to crank it for the first time today and I have no crank. I can see that the BCM is seeing the crank signal from the ignition switch with my scanner but the PCM never gives a starter command. Only code I have that could be the issue is the lost communications with TCM code in the PCM and the TCM not programmed code in the TCM. I can communicate with the TCM with my scanner and I have no CAN bus codes in any module. Also noticed that the gear indicator is not showing park.

Could be a dumb question but I couldn't find a definite answer. Does the 6L80 TCM need to be programmed or written before it will send that data onto the CAN bus? If so then that would probably be the answer to my no crank haha.

[hjtrbo]

might have more luck posting in the trans section

[Alvin]

Yes the 6l80 needs to be programmed.

I'll bet you aren't getting a P/N signal to start. You can try disabling "starter checks" in the system tab

[Phestezio]

Yes the 6l80 needs to be programmed.

I'll bet you aren't getting a P/N signal to start. You can try disabling "starter checks" in the system tab

I had thought about trying that just to see if that makes a difference. I did a quick check of the CAN bus with a meter and everything seems intact and right where it should be. I did look at data in the PCM and it is displaying P/N and in gear when I move the shifter so it seems the PCM is getting the P/N signal. I still no not have a PRNDL indication in the dash and saw quite a few instances of these trucks no crank with it not indicated on the dash. At this point i'm wondering if the BCM is not sending the start request to the PCM since everything in the PCM data seems to say it should be able to crank. But since the ignition switch start signal is a 5v reference input to the BCM and there is no dedicated start output wire from the BCM to the PCM then the start request from the BCM must be CAN data.

I dont have a PID to see what the BCM is seeing for gear position on my scanner so i'm just speculating that the BCM can't see the gear position as P so it's not sending out the start request to the PCM. Can't confirm that other than the PRNDL is controlled by the BCM and its not displaying. From what I have seen i'm pretty confident if I can get the PRNDL to display on the dash then it will probably crank. Why its not displaying though is the question, could that just be from not being programmed?

[Alvin]

I wouldn't make things complicated. If you put that trans in, you should program it also. First step.