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Home >> Chevrolet >> 2009 >> Impala SS >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B2645 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2006 Chevrolet Monte Carlo and 2006 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 volts.
    • If the test lamp is always ON, test the control 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 A and the low reference circuit terminal B. Verify the scan tool Ambient Light Sensor parameter is less than 1.96 volts.
    • 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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