I have a L86 with the 8l90 swap in a project. I am having issues with the transmission, and have the ECM and TCM matched up with the TUN number.
The problem I have been fighting is the truck will go in reverse, but wont go into drive. The Scanner shift PID show Park, Reverse, Neutral, then when I put it down in Drive it says Unknown:82, then Low gear says Unknown:81.
Does anyone have any insight into this, because I am at Wits end. This was a custom built harness by a large harness outfit and I have been through all the pinouts and everything. Any insight would be appreciated, also would be interested in talking to anyone that's a 8l90 transmission Guru.