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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1810 (Lighting System) >> Diagnostic Information and Procedures >> Interior Backlighting Malfunction >> Circuit/System Testing
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Circuit/System Testing

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Dimmer Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
    • 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 0.1 V.
    • If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
  4. Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 15 and ground.
    • If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 V.
    • 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 headlamp and panel dimmer switch.

Interior Backlighting Malfunction

    NOTE:

    Each back lighted component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following:

    • Back lighted components the vehicle is equipped with.
    • Component locations on the back lighting dimming control circuit
    • Each component's control and ground circuit terminals
  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 Ω between the ground circuit and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the Incandescent Dimming or LED Dimming 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 backlighting.

Front Door Switch Backlighting Malfunction

  1. Ignition OFF, disconnect the harness connector X4 at the door lock and side window switch.
  2. Connect a 3 A fused jumper wire between the low reference circuit terminal 4 and ground.
  3. Connect a test lamp between the backlight supply voltage circuit terminal 13 and B+. The heated seat switch backlighting should illuminate.
    • If the switch backlighting does not illuminate, replace the heated seat switch.
  4. If the switch backlighting tests normal, replace the door lock and side window switch.
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