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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 590 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESHEADLAMPS MALFUNCTIONCIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Circuit/System Verification

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Verification
WARNING: This page is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, observe the scan tool Headlamp Switch parameter while turning the headlamp switch ON and OFF. The reading should toggle between ON and OFF.
    • If the reading does not change between the selected states, refer to Turn Signal/Multifunction Switch Malfunction.
  2. Observe the scan tool Headlamp/Parklamp Off Switch parameter while turning the headlamp switch from the PARK and HEAD positions to the OFF position. The parameter change between ON and OFF when changing between the selected states.
    • If the parameter does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
  3. Observe the scan tool Flash to Pass Switch parameter while applying and releasing the flash to pass switch. The parameter should change between Active and Inactive when changing between the selected states.
    • If the parameter does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
  4. Observe the scan tool High Beam Select Switch parameter while applying and releasing the high beam select switch. The parameter should change between Active and Inactive when changing between the selected states.
    • If the parameter does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction.
  5. Command the Low Beams ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when changing between the commanded states.
    • If the low beam headlamps do not turn ON and OFF when commanded, refer to Headlamps Malfunction - Low Beam.
  6. Command the High Beams ON and OFF with a scan tool. The high beam headlamps should turn ON and OFF when changing between the commanded states.
    • If the high beam headlamps do not turn ON and OFF when commanded, refer to Headlamps Malfunction - High Beam.
  7. Ignition ON, with the turn signal/multifunction switch in the neutral position (high beams not ON), apply light through the windshield to the front of the inside rearview mirror. The high beam headlights should dim when the light is detected.
    • If the high beam headlights do not dim, refer to Headlamps Malfunction - High Beam (Intellibeam).
  8. Command the Display Test ON and OFF with a scan tool. The lights on indicator and high beam indicator should turn ON and OFF when changing between the commanded states.
    • If the lights on indicator and high beam indicator illuminate during the test, replace the instrument panel module.
    • If the lights on indicator and high beam indicator do not illuminate during the test or remain illuminated at all times, replace the instrument cluster.
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