Electrical problems are among the most common issues affecting VL Commodores today. Built between 1986 and 1988, the VL introduced a more advanced electrical system than previous Commodores, particularly with its electronic fuel injection (EFI), engine management system, and expanded wiring network.

After more than three decades of use, heat, vibration, corrosion, and ageing components have made electrical faults a regular occurrence. Many starting issues, fuel system problems, charging faults, and intermittent engine troubles can be traced back to the electrical system.

Why Electrical Problems Are Common in VL Commodores

The VL’s electrical system is now over 35 years old.

Main Causes

• Corroded wiring connections
• Poor earth points
• Ageing relays and switches
• Alternator wear
• Damaged wiring insulation
• Moisture intrusion

Many faults are caused by simple deterioration rather than major component failure.

1. Poor Earth Connections

One of the most common electrical issues in VL Commodores.

Symptoms

• Hard starting
• Dim headlights
• Erratic gauges
• Intermittent electrical faults

Causes

• Corrosion at earth points
• Loose earth straps
• Ageing wiring connections

Common Earth Locations

• Battery negative cable
• Engine block earth
• Chassis earth points

Cleaning and restoring earths often fixes multiple problems at once.

2. Alternator Failure

The alternator is responsible for charging the battery and supplying electrical power.

Symptoms

• Battery warning light
• Flat battery after driving
• Dimming headlights
• Slow cranking

Causes

• Worn brushes
• Faulty voltage regulator
• Internal alternator wear

Alternator problems are extremely common in older VLs.

3. Battery Issues

Many electrical faults originate from poor battery condition.

Symptoms

• Slow starting
• Clicking starter motor
• Voltage fluctuations

Causes

• Old battery
• Internal battery failure
• Poor terminal connections

A weak battery can create numerous misleading symptoms.

4. Fuel Pump Relay Problems

A known VL Commodore fault.

Symptoms

• Engine cranks but won’t start
• Intermittent starting problems
• Fuel pump not priming

Causes

• Relay failure
• Corroded terminals
• Heat-related damage

Relay replacement is often a simple fix.

5. Ignition Switch Wear

The ignition switch experiences significant wear over time.

Symptoms

• No crank condition
• Intermittent electrical operation
• Accessories not working correctly

Causes

• Internal contact wear
• Mechanical deterioration

6. Headlight Circuit Problems

Lighting issues are common in ageing VLs.

Symptoms

• Dim headlights
• Flickering lights
• Headlights not operating

Causes

• Poor earths
• Switch wear
• Corroded connectors

7. Instrument Cluster Faults

VL instrument clusters often develop problems.

Symptoms

• Inaccurate gauges
• Flickering warning lights
• Intermittent dash operation

Causes

• Printed circuit deterioration
• Connector corrosion
• Voltage fluctuations

8. ECU Wiring Problems

The VL’s EFI system relies heavily on electrical integrity.

Symptoms

• Poor running
• Random stalling
• No-start conditions
• Faulty sensor readings

Causes

• Wiring deterioration
• Corroded ECU connectors
• Poor earth connections

EFI models are particularly sensitive to voltage issues.

9. Starter Motor Circuit Problems

Not all starting faults are caused by the starter itself.

Symptoms

• Clicking when turning key
• Intermittent no-crank condition
• Voltage drop during starting

Causes

• Worn starter solenoid
• Damaged wiring
• Poor battery cables

10. Electric Window Failures

A common comfort-related electrical problem.

Symptoms

• Slow window movement
• Windows not operating
• Intermittent function

Causes

• Worn switches
• Failing motors
• Wiring faults

11. Fuse Box Problems

The fuse box can become a source of multiple electrical issues.

Symptoms

• Random electrical failures
• Blown fuses
• Intermittent operation

Causes

• Corrosion
• Heat damage
• Loose fuse contacts

12. Charging System Voltage Problems

Incorrect charging voltage can affect the entire vehicle.

Symptoms

• Battery repeatedly going flat
• Flickering lights
• Poor EFI performance

Causes

• Faulty alternator regulator
• Poor wiring connections
• Battery faults

Common VL Turbo Electrical Issues

Turbo models place additional demand on the electrical system.

Common Problems

• Fuel pump voltage drop
• Alternator overload
• ECU grounding issues
• Aftermarket wiring faults

Modified VL Turbos often require electrical upgrades.

How to Diagnose Electrical Problems

Step 1: Check Battery Voltage

A healthy battery should show approximately 12.6 volts with the engine off.

Step 2: Test Charging Voltage

With the engine running, charging voltage should generally be around 13.8–14.4 volts.

Step 3: Inspect Earth Points

Clean and tighten all major earth connections.

Step 4: Check Relays and Fuses

Inspect for corrosion and heat damage.

Step 5: Inspect Wiring

Look for cracked insulation, repairs, or loose connectors.

Best Electrical Upgrades for VL Commodores

Heavy-Duty Battery Cables

Improves starting and charging reliability.

New Earth Straps

Reduces voltage drop and electrical faults.

Upgraded Alternator

Ideal for modified or turbocharged vehicles.

Relay Upgrades

Improves reliability of fuel pumps and lighting circuits.

Preventative Maintenance Tips

Clean Battery Terminals Regularly

Prevents voltage loss.

Inspect Earth Connections Annually

Reduces intermittent faults.

Replace Old Relays

Cheap insurance against breakdowns.

Protect Wiring from Heat

Particularly important around turbochargers.

Warning Signs of Electrical Trouble

• Hard starting
• Flickering lights
• Random stalling
• Inconsistent gauge readings
• Repeated flat batteries

Electrical problems rarely improve on their own and should be investigated early.

Electrical problems in VL Commodores are extremely common due to age, corrosion, and component wear. Fortunately, many issues can be traced to simple faults such as poor earths, weak batteries, worn relays, or ageing wiring.

The key to reliable electrical performance is systematic diagnosis and preventative maintenance. Cleaning connections, upgrading charging components, and replacing ageing electrical parts can dramatically improve reliability.

With proper attention, the VL Commodore electrical system can remain dependable despite being nearly four decades old.

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