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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 590 (LIGHTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESTURN SIGNAL LAMPS AND/OR INDICATORS 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 is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

Turn Signal Switch Malfunction

  1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal G.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Left Front Turn/Hazard Command parameter is Off.
    • If not the specified value, test the signal circuit terminal F for a short to ground. If the circuit tests normal, replace the IPM.
  4. Verify the scan tool Right Front Turn/Hazard Command parameter is Off.
    • If not the specified value, test the signal circuit terminal H for a short to ground. If the circuit tests normal, replace the IPM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal F and ground. Verify the scan tool Left Front Turn/Hazard Command parameter is On.
    • 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 IPM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal H and ground. Verify the scan tool Right Front Turn/Hazard Command parameter is On.
    • 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 IPM.
  7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Turn Signal Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative turn signal/repeater lamp.
  2. Ignition OFF, exterior lamps OFF, test for less than 5 Ξ© between the ground circuit and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and the ground circuit.
  4. Command the appropriate turn signal lamp ON and OFF with the turn signal/multifunction switch. 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 RIM.
    • 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 RIM.
  5. If all circuits test normal, test or replace the appropriate turn signal lamp assembly.

Tail Lamp Outage Detection Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate rear tail lamp assembly.
  2. Ignition ON, test for B+ between the outage detection circuit terminal C and ground.
    • If the measured voltage is less than B+, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RIM.
  3. Ignition ON, connect a test lamp between the outage detection circuit terminal C and ground. The test lamp should not Illuminate.
    • If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the RIM.
  4. If all circuits test normal, test or replace the tail lamp assembly.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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