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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 >> Courtesy Lamps 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 Driver Door Ajar Sw. and Passenger Door Ajar Sw. parameters while opening and closing each vehicle door. The parameters should change between Door Ajar and Door Closed.
  2. Observe the scan tool Rear Closure Ajar Sw. parameter while opening and closing the rear closure door. The parameter should change between Active and Inactive.
  3. All doors closed, observe the scan tool 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 Lamp Switch Malfunction.
  4. Command the Courtesy Lamp ON and OFF with a scan tool. The courtesy lamps should turn ON and OFF when changing between the commanded states.
    • If the courtesy lamps do not turn ON and OFF when commanded, refer to Courtesy Lamp Malfunction.
  5. Turn the individual reading lamps ON and OFF with their respective switches. The reading lamps should turn ON and OFF when changing between the selected states.
    • If any reading lamp does not turn ON and OFF when selected, refer to Inadvertent Power Courtesy Lamps Malfunction.
  6. Turn the left and right sunshade lamps ON and OFF with their respective switches. The sunshade lamps should turn ON and OFF when changing between the selected states.
    • If any reading lamp does not turn ON and OFF when selected, refer to Inadvertent Power Courtesy Lamps Malfunction.
  7. Turn the underhood lamp ON and OFF by opening and closing the hood. The underhood lamp should turn ON and OFF when changing between the selected states.
    • If the rear compartment courtesy lamp does not turn ON and OFF when selected, refer to Inadvertent Power Courtesy Lamps Malfunction.
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