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Home >> Chevrolet >> 2012 >> Traverse LS, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 8 (Lighting System) >> Diagnostic Information and Procedures >> DTC B388A >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the trailer park lamp 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 a short to ground or an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 85 and the B+ circuit terminal 86.
  4. Command the Trailer Park Lamps 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 K9 BCM.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM
  5. If all circuits test normal, test or replace the trailer park lamp relay.
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