Attention: TDR Forum Junkies 
Have a quick question. I’m reinstalling a PacBrake exhaust brake and need some guidance. I’ve utilized a Viair compressor which works fine. The solenoid for the PacBrake isn’t firing, so the brake isn’t coming on. I can get it to come on manually if I tough the wires to a battery, so I know the solenoid is working.
The way I wired it was the wire from the ECU on the side of the engine (forget what pin, but it wasn’t changed or touched for that matter from the previous installation) goes to one side of the solenoid, with the other wire from the solenoid going to ground. I think I have this backwards, where the other wire from the solenoid should go to a 12V power source.
Does anyone know if the ECU switches ground, or power? If it switches ground, the other wire from the solenoid would go to power. I think this is where I went wrong. Wish I took better notes when I disassembled the system.
Thanks.
Dan
The way I wired it was the wire from the ECU on the side of the engine (forget what pin, but it wasn’t changed or touched for that matter from the previous installation) goes to one side of the solenoid, with the other wire from the solenoid going to ground. I think I have this backwards, where the other wire from the solenoid should go to a 12V power source.
Does anyone know if the ECU switches ground, or power? If it switches ground, the other wire from the solenoid would go to power. I think this is where I went wrong. Wish I took better notes when I disassembled the system.
Thanks.
Dan
