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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting >> Diagnostic Information and Procedures >> DTC B2645 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
  2. Ignition OFF, test for less than 1 ohm of resistance between the ground circuit terminal C and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool ambient light sensor parameter is greater than 4.5 volts.
    • If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3A fused jumper wire between the signal circuit terminal D and the low reference circuit terminal C. Verify the scan tool light sensor parameter is less than 1.0 volt.
    • If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the ambient light sensor.
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