So I have a 06 GTO LS2 and T56 in an '80 Corvette. Came with the E40 ECU. I used the factory harness but got the C1 plug aftermarket. It has the yellow wire in pin 42 for Reverse Lockout Solenoid Control. After reading every thread I could find the consensus is that the E40 controls the solenoid with the ground wire. I have the wires from the C101 connector to a fused power source. This includes the light green wire for Reverse Lockout Solenoid (and Skip Shift). The harness has a plug with a yellow and a pink/blue wire that is plugged into the solenoid. Most diagrams have it going to the BCM. I am not using a BCM or PIM. The other advice is to tap into a brake light wire. I would rather the ECU control the function.

So, my question is where the light green wire goes and where it connects with the connector to provide the 12V+. If the yellow from C1 is the ground, where does it tap into the harness and which of the wires on the solenoid is the ground? I have the car running now and don't want to pull the harness or the body to trace down these wires!