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Circuit/System Testing

WARNING: This page is about a different car, the 2010 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X1 harness connector at the BCM.
  2. Connect a test lamp between B+ and the signal circuit terminal 23.
  3. Cycle the headlamp switch between the AUTO and OFF positions. The test lamp should turn ON and OFF as the switch is cycled.
    • If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the turn signal/multifunction switch.
    • If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the turn signal/multifunction switch.
  4. Ignition OFF, disconnect the X2 harness connector at the BCM.
  5. Connect a test lamp between B+ and the signal circuit terminal 12.
  6. Cycle the headlamp switch between the HEAD and OFF positions. The test lamp should turn ON and OFF as the switch is cycled.
    • If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the turn signal/multifunction switch.
    • If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the turn signal/multifunction switch.
  7. Connect a test lamp between B+ and the signal circuit terminal 8.
  8. Cycle the headlamp switch between the PARK and OFF positions. The test lamp should turn ON and OFF as the switch is cycled.
    • If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the turn signal/multifunction switch.
    • If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the turn signal/multifunction switch.
  9. If all circuits test normal, replace the BCM.
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