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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 334 (Lighting System) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify the scan tool Headlamps On Switch parameter changes between Active and Inactive while commanding the headlamp ON and OFF with the turn signal/multifunction switch.
    • If the parameter does not change 

      Refer to Circuit/System Testing - Turn Signal/Multifunction Switch Malfunction.

    • If the parameter changes 
  3. Verify the scan tool Automatic Headlamps Disable Switch parameter changes between Active and Inactive while commanding the automatic lamp control ON and OFF with the turn signal/multifunction switch.
    • If the parameter does not change 

      Refer to Circuit/System Testing - Turn Signal/Multifunction Switch Malfunction.

    • If the parameter changes 
  4. Verify the scan tool Headlamps Flash Switch parameter changes between Active and Inactive while commanding the flash to pass ON and OFF with the turn signal/multifunction switch.
    • If the parameter does not change 

      Refer to Circuit/System Testing - Turn Signal/Multifunction Switch Malfunction.

    • If the parameter changes 
  5. Verify the scan tool High Beam Select Switch parameter changes between Active and Inactive while commanding the high beams ON and OFF with the turn signal/multifunction switch.
    • If the parameter does not change 

      Refer to Circuit/System Testing - Turn Signal/Multifunction Switch Malfunction.

    • If the parameter changes 
  6. Verify the left low beam headlamp turns ON and OFF when commanding the appropriate Low Beam Lamp ON and OFF with a scan tool.
    • If the left low beam headlamp does not turn ON and OFF 

      Refer to Circuit/System Testing - Headlamps Malfunction - Low Beam.

    • If the left low beam headlamp turns ON and OFF 
  7. Verify the right low beam headlamp turns ON and OFF when commanding the appropriate Low Beam Lamp ON and OFF with a scan tool.
    • If the right low beam headlamp does not turn ON and OFF 

      Refer to Circuit/System Testing - Headlamps Malfunction - Low Beam.

    • If the right low beam headlamp turns ON and OFF 
  8. Verify the high beams turn ON and OFF when commanding the High Beams ON and OFF with a scan tool.
    • If the high beams do not turn ON and OFF 

      Refer to Circuit/System Testing - Headlamps Malfunction - High Beam.

    • If the high beams turn ON and OFF 
  9. (TQ5 only), verify the automatic high beam control indicator on the instrument cluster turns ON and OFF while commanding the automatic high beam control ON and OFF with the automatic high beam control switch located on the Turn Signal/Multifunction switch.
    • If the automatic high beam control indicator does not turn ON and OFF 

      Refer to Automatic High Beam Select Switch Malfunction.

    • If the automatic high beam control indicator turns ON and OFF 
  10. All OK.
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