GM Service Manual Online
For 1990-2009 cars only
  1. Perform the Diagnostic System Check - Vehicle.
  2. Using a test lamp, test the power outlet socket supply voltage circuit.
  3. If test lamp does not illuminate, repair or replace the supply voltage circuit.
  4. Using a DMM, test the power outlet socket ground circuit to a known good ground.
  5. 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.