SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2019EXPRESS 2500 BASE, VAN CARGO EXTENDED, 6.0L ENG VIN GREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 39 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESCOURTESY LAMPS MALFUNCTIONCIRCUIT/SYSTEM TESTING
2019 Chevrolet Express 2500 Base, Van Cargo Extended, 6.0L Eng VIN G

Circuit/System Testing

2019 Chevrolet Express 2500 Base, Van Cargo Extended, 6.0L Eng VIN GSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 GMC Savana 3500, 2018 GMC Savana 2500, 2018 Chevrolet Express 3500, and 2018 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Dome Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON with all doors closed, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.
    • If not the specified value, test the signal circuits listed below for a short to ground. If the circuits test normal, replace the BCM.
    • Terminal 9
    • Terminal 12
  4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and ground. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 9 and ground. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate dome lamp.
  2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal A and ground.
  4. Command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the dome lamp.

Inadvertent Power Courtesy Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate courtesy lamp.
  2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the appropriate B+ circuit terminal listed below and ground.
    • Courtesy/Reading Lamp - terminal C
    • Sunshade Lamp - terminal A
    • Underhood Lamp - terminal A
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, test or replace the courtesy lamp.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.