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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1285 (Suspension Control System - Automatic Level Control) >> Diagnostic Information and Procedures >> DTC C0660 >> Circuit/System Testing
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Circuit/System Testing

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  1. Ignition OFF, disconnect the automatic level control (ALC) compressor exhaust solenoid.
  2. Ignition ON, verify that a test lamp does not illuminate between the solenoid control circuit terminal C at the connector 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 B+ circuit terminal B and ground.
    • If the test lamp does not illuminate, test the B+ circuits for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the ALC compressor.
  4. Connect a test lamp between the B+ circuit terminal B and the control circuit terminal C.
  5. With a scan tool, clear all ALC DTCs.
  6. Command the exhaust solenoid ON and OFF. 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 ESCM.
    • 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 ESCM.
  7. If all circuits test normal, test or replace the ALC compressor.
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