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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1518 (Fixed And MOVEABLE Windows) >> Diagnostic Information and Procedures >> DTC B0285 or B0286 >> Circuit/System Testing >> Rear Defogger Malfunction

Rear Defogger Malfunction

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the REAR DEFOG relay.
  2. Ignition OFF, test for less than 1 ohm of resistance between the coil side ground circuit terminal and ground.
    • If greater than the specified range, test for an open/high resistance.
  3. Connect a test lamp between the coil side control circuit terminal and the coil side ground circuit terminal.
  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 test 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 DEFOG relay.
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