BCM Code B420, Courtesy Light Relay Circuit (2 Of 5): Notes

If courtesy lights did not cycle on and off when BO04 was selected, then courtesy lights relay have set Code B420.

1. Checks to see if fault is due to an open circuit or a short to ground in the circuit. If courtesy lights are always on, then there is a short in control circuit. If courtesy lights never turn on, then there is an open in one of the circuits.
2. Checks to see if short to ground is due to circuit or BCM.
3. Checks to see if open circuit is due to circuit or BCM.
4. Checks to see if open circuit is on power side of relay.
5. Checks if open circuit is on ground side of relay or if relay is at fault.