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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1221 (Lighting Systems) >> Diagnostic Information & Procedures >> DTC B2540 >> Circuit/System Testing
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Circuit/System Testing

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  1. Ignition OFF, disconnect the harness connector at the headlamp switch.
  2. Verify that a test lamp illuminates between B+ and the ground circuit terminal 8.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Rear Fog Lamp Switch parameter is INACTIVE.
    • If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the XBCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 6 and ground. Verify the scan tool Rear Fog Lamp Switch parameter is ACTIVE.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the XBCM.
  5. If all circuits test normal, test or replace the headlamp switch.
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