From the PDC(fuse block under hood) , fuse #11 supplies the voltage. From here, the circuit will run to the junction block (fuse block inside the cab under the instrument panel). There will be a 30amp circuit breaker. This circuit is Tan in color that will run through the wiring harness boot on the door jamb to the master switch. This should have battery voltage with the key on, engine off. Black is ground.