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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the K55 rear window defogger relay.
  2. Test for less than 1 Ω between the ground circuit terminal 86 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify 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 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. Ignition OFF, disconnect the X2 harness connector at the E18 rear defogger grid.
  6. Test for less than 5 Ω between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the X2 harness connector at the E18 rear defogger grid.
  8. Ignition ON, connect a 40 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the E18 rear defogger grid is activated.
    • If the E18 rear defogger grid does not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the E18 rear defogger grid.
  9. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
  10. Engine running, command the Rear Defog 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 K33 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 K33 HVAC control module.
  11. If all circuits test normal, test or replace the K55 rear window defogger relay.
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