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Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the HORN relay.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 86 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit fuse is open, test the control circuit terminal 87 for a short to ground. If all circuits test normal, test or replace the HORN relay.
  3. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
  4. Command the horns 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 OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM
  5. If all circuits test normal, test or replace the HORN relay.
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