FixVault

Circuit/System Testing

  1. Ignition OFF, disconnect the rear window defog relay.
  2. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal 86 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the rear defog relay control circuit terminal 85 and ground.
  4. Command the rear defog relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the rear window defog relay.