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Home >> Cadillac >> 2009 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 163 (Suspension Control System - Automatic Level Control) >> Diagnostic Information and Procedures >> DTC C0712 >> Circuit/System Testing
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Circuit/System Testing

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  1. Ignition OFF, disconnect the ALC relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the relay connector control circuit terminal 86 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 connector B+ circuit terminal 85 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 relay coil B+ circuit for a short to ground. If all circuits test normal, test or replace the ELC relay.
  4. Verify that a test lamp illuminates between the relay connector B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay coil B+ circuit and compressor control circuit for a short to ground or a faulty ALC compressor motor. If all circuits test normal, test or replace the ELC relay.
  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 G 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 40-A fused jumper wire between the relay connector B+ circuit terminal 30 and the relay connector control circuit terminal 87. 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 relay connector B+ circuit terminal 85 and the relay connector control circuit terminal 86.
  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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