I can't tell you exactly how to do it but I can give you an idea to look into. I'm pretty sure it's a momentary contact switch that triggers the computer. You need a relay that closes the contacts that engage the exhaust brake, that's triggered by something that you do every time you drive. I'm thinking maybe a micro switch on the shifter that triggers the relay when you take it out of park. You probably want it to trigger momentarily as the shifter sweeps by and not constant contact. Someone more familiar with how the circuit works can advise you on that. As suggested above, I'd also connect it to tow/haul mode.Has anyone found a way to turn the exhaust brake on and leave it on so you don't have to set it every time you start it?