Commodore (VN-VZ) / HSV

1988-2006 / Sedan / Estate / Australia

All Commodore (VN-VZ) / HSV problems All workshop issues

Common Electrical

Body Control Module (BCM) Issues (VT-VZ)

Symptoms

Intermittent electrical faults, interior lights stay on, power windows stop working, central locking misbehaves, dashboard warning lights illuminate randomly, the car may not crank.

Cause

The BCM is the central control module for the body electrics. It communicates with the engine control module (ECM), instrument cluster, and various sub-systems via CAN-bus wiring. The BCM can develop internal faults from age, moisture ingress, or power surges. The connector pins can also corrode.

Fix

Diagnosis first, a Tech2 or compatible scan tool can read BCM fault codes.

Connector cleaning sometimes resolves intermittent issues.

A faulty BCM must be replaced and programmed to the car's VIN and immobiliser system.

A secondhand BCM needs programming: $100-200 at an auto electrician.

A new BCM from the dealer (where available) is $300-600.

Cost mentioned in fix

$100-200$300-600

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Other known issues

Common Electrical

Alternator Failure

Battery warning light on the dash, dim headlights, accessories losing power, battery going flat.

Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Intake Manifold Gasket Leak

Coolant leak at the junction of the intake manifold and cylinder heads. May present as coolant loss without a visible external leak (coolant enters the intake ports), or as a coolant stain on the side of the engine. Engine may run rough or misfire if coolant enters the combustion chamber.

Critical Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Harmonic Balancer Failure (Ecotec, VS onwards)

A wobbling pulley on the front of the crankshaft. Knocking or rattling noise from the front of the engine. The drive belt may track poorly or come off.

Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Supercharger Bypass Valve Failure (L67 supercharged V6)

Loss of boost, rattling from the supercharger, reduced performance. The supercharger may make a whining noise that changes with the valve's operation.

Critical Engine, V6 (Alloytec 3.6L, VZ)

Timing Chain and Guide Failure

Rattling noise on cold start that may persist after warm-up. Check engine light with codes related to camshaft timing. Rough idle, misfiring, loss of power. In severe cases, the engine won't start or runs extremely poorly.

Critical Engine, V6 (Alloytec 3.6L, VZ)

Oil Leaks from Timing Cover

Oil weeping or dripping from the front of the engine, behind the harmonic balancer area.

View all 20 Commodore (VN-VZ) / HSV problems