I have a 2007 LS-swapped LR Defender (2011 Corvette LS3 [E38] & 2010 Camaro 6L80E[T43]). When I shift into drive or reverse with brakes fully applied (handbrake fully engaged as well), there is a not so friendly jerk on the U-joints and the wheels keep spinning. I have wired the brake signal using a 5 pin relay such that it has ground when the brake pedal is pressed & 12V at all other times. The brake state works fine when the engine is OFF (verified on HPtuners VCM scanner), but with the engine running it doesn't. I believe this is the reason the TCC seems to stay locked up when I shift to drive or reverse, even when I step on the brakes.

Has anyone faced this issue before? I would appreciate any piece of information right now, Thanks in advance