LEMON Manuals: Even more car manuals for everyone
Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> Body & Frame >> Fixed And MOVEABLE Windows >> Diagnostic Information and Procedures >> Rear Window Defogger Malfunction (SUT) >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the REAR DEFOG relay.
  2. Test for less than 1 ohm between the ground circuit terminal 85 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  5. Disconnect the harness connector at the midgate control module.
  6. Ignition ON, connect a 30A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
  7. Verify a test lamp illuminates between the control circuit terminal listed below and ground:
    • Control circuit terminal 13
    • Control circuit terminal 15
    • If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance.
  8. Ignition OFF, connect the harness connector at the midgate control module and disconnect the harness connector at the rear window defogger.
  9. Test for less than 1 ohm between the rear window defogger ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  10. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 4 and ground.
    • If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the midgate control module.
  11. If the circuit tests normal, test or replace the rear window defogger.
  12. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  13. Command the rear window defogger 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 HVAC control module.
    • 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 HVAC control module.
  14. If all circuits test normal, test or replace the REAR DEFOG relay.
scientia non olet · About LEMON Manuals