SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1238 (ENGINE COOLING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P0480 OR P0481CIRCUIT/SYSTEM TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Chevrolet Malibu Classic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the series/parallel relay, which is cool/fan SER/PAR relay 29.
  2. Connect a 30A fused jumper between the normally-open switch contact terminals 30 and 87 at the series/parallel relay connector in order to complete the fan ground circuit. Leave this jumper in place for the remainder of this procedure.
  3. Ignition OFF, disconnect the affected relay.
  4. Verify that a test lamp does not illuminate between B+ and the affected relay control circuit terminal 85.
  5. Remove the test lamp.
  6. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt. Short Volts Test Status Parameter is OK.
    • If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  7. Install a 3A fused jumper wire between the control circuit terminal 85 and B+. Command the affected relay ON with a scan tool. Verify the scan tool Relay Control Ckt Short Volts Test Status Parameter is Fault.
    • If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  8. Remove the 3A fused jumper wire.
  9. Connect a 30A fused jumper between the positive voltage terminal at the battery and the fan voltage supply circuit terminal at the affected relay connector and verify fan activation.
    • Cooling Fan Relay 1 and Cooling Fan Relay 2 = Terminal 87
    • Cooling Fan Series/Parallel Relay = Terminal 87A
    • If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan.
  10. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal 30 and the fan voltage supply circuit terminal 87 at the affected relay connector and verify fan activation.
    • If the fan does not activate, test the affected relay switch voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.
  11. Ignition ON, verify that a test lamp illuminates between the affected relay coil voltage supply circuit terminal and ground.
    • Cooling Fan Relay 1 and Cooling Fan Relay 2 - Terminal 86
    • Cooling Fan Series/Parallel Relay = Terminal 85
    • If the test lamp does not illuminate, test the affected relay coil voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.
  12. If all circuits and the ECM test normal, replace the affected relay.
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.