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Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.

Dimmer Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the I/P Dimmer switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool dimming control signal parameter is less than 0.0 volts.
    • If greater than the specified range, test the signal circuit terminal 9 for a short to voltage. If the circuit tests normal, replace the BCM.
  4. Ignition ON, test for B+ between the voltage reference circuit terminal 5 and ground.
    • If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If greater than the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 9 and the B+ reference circuit terminal 5. Verify the scan tool dimming control signal parameter is greater than 2.5 volts.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the I/P dimmer switch.

Interior Backlighting Malfunction (Incandescent)

  1. Ignition OFF, disconnect the harness connector at the component with the inoperative incandescent backlighting.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the I/P lamps dimmer switch signal circuit and ground.
  4. Command the incandescent dimming control 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 ground 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 voltage. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the component with the inoperative incandescent backlighting.

Interior Backlighting Malfunction (LED)

  1. Ignition OFF, disconnect the C3 harness connector at the BCM.
  2. Ignition ON, verify that a test lamp illuminates between the BCM 2 fuse voltage supply circuit terminal 2 and ground.
    • If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, reconnect the C3 harness connector at the BCM.
  4. Ignition OFF, disconnect the harness connector at the component with the inoperative LED backlighting.
  5. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the dimming control circuit and ground.
  7. Command the LED dimming control 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 ground 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 voltage. If the circuit tests normal, replace the BCM.
  8. If all circuits test normal, test or replace the component with the inoperative LED backlighting.

HVAC Fan Speed/Rear Window Defogger Indicator Malfunction

  1. Ignition OFF, disconnect the C3 harness connector at the HVAC control module.
  2. Connect a test lamp between the control circuit terminal 1 and ground.
  3. Command the LED dimming control 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 ground 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 voltage. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the HVAC control module.

Front Door Switch Indicator Malfunction

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