Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1401 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B3435 OR B3440CIRCUIT/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 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the appropriate headlamp leveling motor.
- Ignition OFF, test for less than 10.0 ohms between the motor control circuit terminal 1 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
- Ignition OFF, test for less than 10.0 ohms between the motor control circuit terminal 2 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
- Ignition OFF, test for less than 10.0 ohms between the motor control circuit terminal 3 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
- Ignition OFF, test for less than 10.0 ohms between the motor control circuit terminal 4 and ground.
- If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the headlamp control module.
- Connect a test lamp between control circuit terminal 1 and control circuit terminal 3.
- Command the DHL motor control to the UP and DOWN positions with a scan tool. The test lamp should turn ON when commanding the UP and DOWN states.
- If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the headlamp control module.
- Connect a test lamp between control circuit terminal 2 and control circuit terminal 4.
- Command the DHL motor control to the UP and DOWN positions with a scan tool. The test lamp should turn ON when commanding the UP and DOWN states.
- If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the headlamp control module.
- If all circuits test normal, replace the appropriate headlamp assembly.
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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.