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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 731 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSTOP LAMPS MALFUNCTIONCIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G3500, Van Passenger Extended

Circuit/System Testing

2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Stop Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
  2. Ignition ON, test for battery voltage between the 12 V reference circuit terminal C and ground.
    • If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  3. Verify the scan tool Stop Lamp Switch Status parameter is approximately 2 counts.
    • If not the specified value, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal D and the 12 V reference circuit terminal C. Verify the scan tool Stop Lamp Switch Status parameter is approximately 1023 counts.
    • If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the stop lamp switch.

Stop Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector X4 at the BCM.
  2. Ignition ON, verify a test lamp illuminates between the stop lamp B+ terminal 4 and ground.
    • If the test lamp does not illuminate, and the STOP LAMPS fuse tests normal, test the B+ circuit for a short to ground or an open/high resistance.
  3. Connect the harness connector X4 at the BCM.
  4. Ignition OFF, disconnect the harness connector at the appropriate stop lamp.
  5. Test for less than 5 Ξ© between the ground circuit terminal of the harness connector listed below and ground.
    • Tail/Stop and Turn Signal Lamp - Left and Right - Upper and Lower terminal GRD - with Z75 - E52
    • Tail Lamp Circuit Board - Left and Right terminal D - with Z75 + E52 and European
    • Tail/Stop Lamp - Left and Right terminal GRD - with X88
    • Tail/Stop Lamp - Left and Right terminal G - Z88
    • Tail/Stop Lamp - Left and Right terminal 2 - with HP2
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the stop lamp control circuit terminal listed below and ground circuit terminal.
    • Tail/Stop and Turn Signal Lamp - Left and Right - Upper and Lower terminal MJR - with Z75 - E52
    • Tail Lamp Circuit Board - Left and Right terminal E - with Z75 + E52 and European
    • Tail/Stop Lamp - Left and Right terminal MJR - with X88
    • Tail/Stop Lamp - Left and Right terminal A - Z88
    • Tail/Stop Lamp - Left and Right terminal 1 - with HP2
  7. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected states.
    • If the test lamp is always ON, test the control circuit for a short to voltage.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
  8. If all circuits test normal, test or replace the stop lamp.

Center High Mounted Stop Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector X4 at the BCM.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
  3. Reconnect the harness connector X4 at the BCM.
  4. Ignition OFF, disconnect the harness connector at the center high mounted stop lamp.
  5. Test for less than 5 Ξ© between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the stop lamp control circuit terminal A and ground circuit terminal B.
  7. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected 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.
  8. If all circuits test normal, test or replace the center high mounted stop lamp.
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When to See a Mechanic

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

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