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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the ALC compressor.
  2. Ignition ON, verify that a test lamp illuminates between the ALC compressor connector B+ circuit terminal C 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 ELC fuse is open, test or replace the ALC compressor.
  3. Connect a test lamp between the ALC compressor connector control circuit terminal A and the B+ circuit terminal C.
  4. Command the exhaust valve solenoid 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 ESCM.
    • If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ESCM.
  5. If all circuits test normal, test or replace the ALC compressor.
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