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Home >> Cadillac >> 2007 >> STS Base, 4.6 A, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 12 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B2645 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac SRX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the sunload sensor assembly.
  2. Ignition OFF, scan tool OFF, doors CLOSED, test for less than 20.0 ohms of resistance between the low reference circuit terminal C and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  3. Reconnect the sunload sensor assembly harness connector.
  4. Ignition ON, verify the scan tool ambient light sensor parameter is greater than 0.2 volts.
    • If less than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
  5. Verify the scan tool ambient light sensor parameter is less than 4.9 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.
  6. If all circuits test normal, replace the sunload sensor assembly.
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