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Home >> Cadillac >> 2009 >> STS Base, 4.6 A, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Suspension Control System - Automatic Level Control) >> Diagnostic Information and Procedures >> DTC C0712 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the ELC relay from the rear fuse block.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal R8 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay B+ circuit terminal R7 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal R8 for a short to ground or faulty ALC compressor motor. If all circuits test normal, test or replace the ELC relay.
  4. Verify that a test lamp illuminates between the relay B+ circuit terminal R6 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the air compressor.
  6. Test for less than 1 ohm of resistance between the ALC compressor ground circuit terminal D and ground.
    • If greater than 1 ohm, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the ALC compressor.
  8. Connect a 40A fused jumper wire between the relay B+ circuit terminal R7 and the control circuit terminal R8. Verify the ALC compressor is activated.
    • If the ALC compressor does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the ALC compressor.
  9. Connect a test lamp between the B+ circuit terminal R6 and the control circuit terminal R10.
  10. Command the ALC compressor 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 ground. If the circuit tests normal, replace the electronic suspension control module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the electronic suspension control module.
  11. If all circuits test normal, test or replace the ELC relay.
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