For 1990-2009 cars

1. Perform the Diagnostic System Check - Vehicle.
2. Using a test lamp, test the power outlet socket supply voltage circuit.

⇒ | If test lamp does not illuminate, repair or replace the supply voltage circuit.

3. Using a DMM, test the power outlet socket ground circuit to a known good ground.

⇒ | If DMM indicates that the circuit is not intact, repair or replace the ground circuit.

⇒ | If DMM indicates that the circuit is intact, replace the power outlet socket.