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Home >> Chevrolet >> 2019 >> Suburban 3500 HD LS >> Repair and Diagnosis >> Accessories & Equipment >> Exterior Lights >> Lighting System - Diagnostic Information And Procedures (DTC B3950-C0297) >> Diagnostic Information and Procedures >> Headlamps Malfunction (Chevrolet, GMC) >> Circuit/System Verification

Circuit/System Verification

  1. Ignition ON.
  2. Verify ALL turn signals operate when activated with the turn signal switch.
    • Go to next step: If the turn signals operate when activated 
  3. Verify the scan tool Headlamps On Switch parameter changes between Active and Inactive while commanding the headlamps ON and OFF with the headlamp switch.
    • If the parameter does not change 

      Refer to Headlamp Switch Malfunction.

    • Go to next step: If the parameter changes 
  4. 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 headlamp switch.
    • If the parameter does not change 

      Refer to Headlamp Switch Malfunction.

    • Go to next step: If the parameter changes 
  5. 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 Turn Signal/Multifunction Switch Malfunction.

    • Go to next step: If the parameter changes 
  6. 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 Turn Signal/Multifunction Switch Malfunction.

    • Go to next step: If the parameter changes 
  7. Verify the left low beam headlamp turns ON and OFF when commanding the Left Low Beam/Daytime Running Lamp ON and OFF with a scan tool.
    • If the left low beam headlamp does not turn ON and OFF 

      Refer to Headlamps Malfunction - Low Beam.

    • Go to next step: If the left low beam headlamp turns ON and OFF 
  8. Verify the right low beam headlamp turns ON and OFF when commanding the Right Low Beam/Daytime Running Lamp ON and OFF with a scan tool.
    • If the right low beam headlamp does not turn ON and OFF 

      Refer to Headlamps Malfunction - Low Beam.

    • Go to next step: If the right low beam headlamp turns ON and OFF 
  9. 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 Headlamps Malfunction - High Beam.

    • Go to next step: If the high beams turn ON and OFF 
  10. Verify the high beam indicator on the instrument cluster turns ON and OFF while commanding the All Indicators Test ON and OFF with a scan tool.
    • If the high beam indicator does not turn ON and OFF 

      Refer to High Beam Indicator Malfunction.

    • Go to next step: If the high beam indicator turns ON and OFF 
    11. NOTE:

    Placing a towel over the ambient light sensor can simulate a dim light condition and shining an incandescent light at the ambient light sensor can simulate a bright light condition.

  11. Verify the scan tool Ambient Light Status parameter changes while switching from dim to bright ambient light conditions
    • If the parameter does not change 

      Refer to Ambient Light Sensor Malfunction.

    • Go to next step: If the parameter changes 
  12. A fault is not currently present and may be an intermittent condition.
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