LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 18 (Lighting System) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, observe the scan tool Auto Hdlp. Disable Sw. parameter while turning the headlamp switch between the OFF, Auto and Park positions. The reading should change between Active and Inactive.
    • If the reading does not change between the specified values, refer to Headlamp Switch Malfunction.
  2. With the headlamps ON, observe the scan tool Flash to Pass Switch parameter while applying and releasing the turn signal/multifunction switch. The reading should change between Active and Inactive.
    • If the reading does not change between the specified values, refer to Turn Signal/Multifunction Switch Malfunction.
  3. Observe the scan tool High Beam Select Switch parameter while switching the turn signal/multifunction switch between the low and high beam positions. The reading should change between Active and Inactive.
    • If the reading does not change between the specified values, refer to Turn Signal/Multifunction Switch Malfunction.
  4. Command the Low Beams ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when commanded.
    • If the low beam headlamps do not turn ON and OFF as commanded, refer to Headlamps Malfunction - Low Beam.
  5. Command the High Beams ON and OFF with a scan tool. The high beam headlamps should turn ON and OFF when commanded.
    • If the high beam headlamps do not turn ON and OFF as commanded, refer to Headlamps Malfunction - High Beam.
  6. Command the Lamp Test ON and OFF with a scan tool. The high beam indicator should turn ON and OFF when changing between the commanded states.
    • If the high beam indicator illuminates during the test, replace the BCM.
    • If the high beam indicator does not illuminate during the test or remain illuminated at all times, replace the instrument cluster.
scientia non olet · About LEMON Manuals