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Home >> GMC >> 2006 >> Sierra 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 981 (Lighting Systems) >> Diagnostic Information and Procedures >> Courtesy Lamps Malfunction (w/o AN3) >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, command the Courtesy Lamps output control on and off with the scan tool. The interior courtesy lamps should turn on and off.
    • If one or more of the courtesy lamps are always on or always off refer to the courtesy lamp control circuit test below.
  2. Observe the scan tool BCM, Driver Door Open Sw. parameter while opening and closing the driver door. The reading should change between Open and Closed.
    • If the Driver Door Open Sw. parameter does not change between Open and Closed, refer to Driver Door Open Switch Test below.
  3. Observe the scan tool BCM, Passenger Door Open Sw. parameter while opening and closing the front passenger door. The reading should change between Open and Closed.
    • If the Passenger Door Open Sw. parameter does not change between Open and Closed, refer to Passenger Door Open Switch Test below.
  4. Observe the scan tool BCM Passenger Door Open Sw. parameter while opening and closing each rear doors one at a time. The reading should change between Open and Closed.
    • If the Ctsy. Lamp Actv. Reason parameter does not change between Open and Closed, refer to Passenger Door Open Switch Test below.
  5. Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the dome lamp switch ON and OFF. The reading should change between Off and Manual.
    • If the Ctsy. Lamp Actv. Reason parameter does not change between Off and Manual, refer to Dome/Interior Lamp Switch Test below.
  6. Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the interior lamp defeat switch ON and OFF. The reading should change between Off and Manual Defeat.
    • If the Ctsy. Lamp Actv. Reason parameter does not change between Off and Manual, refer to Dome/Interior Lamp Switch Test below.
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