HZ Holden Wiring Diagram: An Essential Guide for Electrical System Maintenance

Welcome to the comprehensive guide to the HZ Holden wiring diagram. This document provides a detailed overview of the electrical system, including its components, operation, and troubleshooting procedures. Whether you’re a seasoned mechanic or a DIY enthusiast, this guide will equip you with the knowledge and understanding to maintain and repair your HZ Holden’s electrical system with confidence.

The HZ Holden’s electrical system is a complex network of wires, fuses, relays, and components that work together to power and control various functions of the vehicle. Understanding the wiring diagram is crucial for diagnosing and resolving electrical issues, ensuring the optimal performance and safety of your Holden.

Electrical System Overview

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The HZ Holden electrical system is a complex network of components that work together to provide power, lighting, and control to various functions of the vehicle. The system is designed to be reliable and efficient, and it is essential for the safe and proper operation of the vehicle.The electrical system is divided into several subsystems, each of which has its own specific function.

These subsystems include the starting and charging system, the lighting system, the ignition system, the fuel system, and the body control system.The starting and charging system is responsible for starting the engine and providing power to the electrical system when the engine is running.

The lighting system provides illumination for the driver and passengers, and it also includes the turn signals, brake lights, and headlights. The ignition system is responsible for providing the spark that ignites the fuel in the engine. The fuel system is responsible for delivering fuel to the engine.

The body control system is responsible for controlling various functions of the vehicle, such as the door locks, windows, and seats.The electrical system is connected by a wiring harness that runs throughout the vehicle. The wiring harness is a complex network of wires that connect the various components of the electrical system.

The wiring harness is designed to be durable and reliable, and it is essential for the proper operation of the electrical system.

Fuse and Relay Locations

Fuses and relays play a crucial role in safeguarding the electrical system of a Holden vehicle. They act as protective devices, preventing damage to electrical components and wiring in the event of electrical faults or overloads.

To ensure the smooth functioning of the electrical system, it is essential to have a clear understanding of the location and purpose of all fuses and relays.

Fuse and Relay Box Locations

  • Under-Hood Fuse Box:Located in the engine compartment, typically near the battery or firewall.
  • Passenger Compartment Fuse Box:Situated beneath the dashboard, accessible from the driver’s side footwell.
  • Rear Fuse Box:Found in the trunk or cargo area, usually behind a panel or trim piece.

Fuse and Relay Identification

Fuses and relays are typically identified by their amperage rating and/or function. The amperage rating indicates the maximum current that the fuse can safely handle before blowing. Relays, on the other hand, are electromagnetic switches that control the flow of electricity to specific circuits.

The fuse and relay box covers usually provide a diagram or chart that identifies the location and function of each component.

Role of Fuses and Relays


  • Protect electrical circuits from overcurrent conditions.
  • Blow (open the circuit) when the current exceeds the rated amperage, preventing damage to electrical components.
  • Are designed to be easily replaced when blown.


  • Control the flow of electricity to high-current circuits.
  • Act as switches, using a small amount of current to control a larger current.
  • Protect electrical components from damage due to high current draw.

Battery and Charging System

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The battery and charging system work together to provide electrical power to the vehicle’s electrical components and to start the engine. The battery stores electrical energy, while the charging system generates electricity and recharges the battery.

The battery is a lead-acid battery, which consists of a series of lead plates immersed in an electrolyte solution. When the battery is connected to a circuit, a chemical reaction occurs between the plates and the electrolyte, which produces an electrical current.

The amount of electrical current that the battery can produce is determined by its size and condition.

The charging system consists of an alternator, a voltage regulator, and a rectifier. The alternator is a generator that converts mechanical energy from the engine into electrical energy. The voltage regulator controls the output voltage of the alternator, and the rectifier converts the alternating current (AC) produced by the alternator into direct current (DC), which is used by the vehicle’s electrical components.

The process of battery charging begins when the engine is running. The alternator generates electricity, which is then sent to the battery through the voltage regulator. The voltage regulator ensures that the battery is not overcharged, which can damage the battery.

The rectifier converts the AC electricity produced by the alternator into DC electricity, which is then stored in the battery.

Common battery and charging system faults include:

  • Dead battery
  • Weak battery
  • Faulty alternator
  • Faulty voltage regulator
  • Faulty rectifier

Ignition System

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The ignition system is responsible for creating the spark that ignites the air-fuel mixture in the engine’s cylinders. It consists of several key components:

  • Distributor:Distributes the spark to the correct spark plug at the appropriate time.
  • Ignition Coil:Converts the battery’s low voltage into a high voltage required to create the spark.
  • Spark Plugs:Create the spark that ignites the air-fuel mixture.

The ignition system operates in a synchronized sequence:

  1. The distributor receives a signal from the engine’s camshaft, which determines the timing of the spark.
  2. The distributor sends a low-voltage signal to the ignition coil.
  3. The ignition coil amplifies the signal and sends a high-voltage current to the spark plugs.
  4. The spark plugs create a spark across their electrodes, igniting the air-fuel mixture.

Common Ignition System Faults

Ignition system faults can manifest in various ways, including:

  • Engine misfiring:Caused by a weak or absent spark, resulting in rough engine operation.
  • Engine stalling:Can occur if the ignition system fails completely.
  • Difficulty starting:Ignition system issues can make it difficult for the engine to start.

Troubleshooting Ignition System Faults

Troubleshooting ignition system faults involves:

  1. Checking for spark:Use a spark plug tester to determine if the spark plugs are receiving a spark.
  2. Inspecting the distributor:Ensure the distributor cap and rotor are clean and undamaged.
  3. Testing the ignition coil:Use a multimeter to measure the coil’s resistance and voltage output.
  4. Replacing faulty components:If the spark plugs, distributor, or ignition coil are faulty, replace them.

Lighting System

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The lighting system is a crucial component of any vehicle, ensuring visibility and safety during nighttime driving. It consists of various components that work together to illuminate the road and signal the vehicle’s presence to other drivers.


Headlights are the primary source of illumination for nighttime driving. They are typically mounted on the front of the vehicle and emit a powerful beam of light. Modern headlights use various technologies, including halogen, HID (high-intensity discharge), and LED (light-emitting diode) bulbs.

Each technology offers different levels of brightness, efficiency, and longevity.

Taillights, Hz holden wiring diagram

Taillights are located at the rear of the vehicle and serve several purposes. They provide visibility to other drivers, indicating the vehicle’s position and braking intentions. Taillights typically consist of brake lights, turn signals, and reverse lights.

Other Lighting

In addition to headlights and taillights, various other lighting components contribute to the vehicle’s overall visibility. These include:

Side marker lights

Located on the sides of the vehicle, these lights indicate the vehicle’s width and enhance visibility in low-light conditions.

License plate lights

Illuminate the license plate, making it visible to law enforcement and other drivers.

Interior lights

Provide illumination within the vehicle’s cabin for passenger comfort and convenience.

Dash lights

Illuminate the instrument panel, allowing drivers to monitor vehicle information and controls.

Wiring and Connections

The lighting system is connected to the vehicle’s electrical system through a complex network of wires and connectors. These wires carry electrical current from the battery to the various lighting components. The wiring harness is designed to ensure proper distribution of power and prevent electrical faults.Proper maintenance and repair of the lighting system are essential for ensuring safe and effective operation.

Regular inspection of bulbs, lenses, and wiring can help identify and address any potential issues before they become a hazard.

Instrument Cluster

The instrument cluster is the central hub for displaying critical information to the driver. It provides real-time data on the vehicle’s performance, system status, and alerts.The instrument cluster typically consists of several gauges, indicators, and warning lights. Gauges measure and display vital parameters such as speed, engine RPM, fuel level, and coolant temperature.

Indicators provide information about the status of various systems, such as turn signals, headlights, and seat belts. Warning lights illuminate to alert the driver of potential issues, such as low tire pressure, engine malfunctions, or safety concerns.

Wiring and Connections

The instrument cluster is connected to the vehicle’s electrical system through a complex network of wires and connectors. These connections transmit data from sensors and modules throughout the vehicle to the instrument cluster, allowing it to display the necessary information to the driver.

The wiring and connections are designed to ensure reliable communication and minimize interference from other electrical components.

HVAC System

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The HVAC system in the HZ Holden is responsible for providing heating, ventilation, and air conditioning within the vehicle’s cabin. It consists of several key components that work together to regulate the temperature and airflow within the car.

Heating System

The heating system in the HZ Holden utilizes a heater core that is connected to the engine’s cooling system. When the heater is turned on, hot coolant from the engine flows through the heater core, warming the air that passes through it.

This warm air is then distributed throughout the cabin via vents located on the dashboard and floor.

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Ventilation System

The ventilation system in the HZ Holden is responsible for circulating fresh air throughout the cabin. It consists of a series of vents and ducts that allow air to enter the cabin from outside and circulate it throughout the interior.

The ventilation system can be controlled manually or automatically, allowing the driver to adjust the airflow as needed.

Air Conditioning System

The air conditioning system in the HZ Holden utilizes a compressor, condenser, evaporator, and expansion valve to cool the air within the cabin. When the air conditioning is turned on, the compressor compresses refrigerant gas, which then flows through the condenser where it is cooled and condensed into a liquid.

The liquid refrigerant then flows through the expansion valve, where it is converted back into a gas and expands, causing it to cool. The cooled gas then flows through the evaporator, where it absorbs heat from the air in the cabin, cooling it down.

The cooled air is then distributed throughout the cabin via vents located on the dashboard and floor.

Wiring and Connections

The HVAC system in the HZ Holden is powered by the vehicle’s electrical system and controlled by a series of switches and sensors. The wiring and connections for the HVAC system are complex and should only be serviced by a qualified technician.

Body Electrical: Hz Holden Wiring Diagram

The body electrical system encompasses the wiring and connections for various components, including windows, locks, and mirrors. It ensures the proper functioning of these accessories, enhancing the convenience and comfort of the vehicle.

Power accessories, such as power windows and locks, are integrated with the electrical system, allowing for effortless operation at the touch of a button. These accessories draw power from the vehicle’s battery and are controlled by switches or modules that regulate their operation.

Common Body Electrical Faults and Troubleshooting

Common body electrical faults can include issues with window operation, lock malfunctions, or mirror adjustment problems. Troubleshooting these faults involves systematic checks of the electrical components, wiring, and switches.

  • Window Operation Faults:Check for faulty switches, damaged wiring, or issues with the window motor or regulator.
  • Lock Malfunctions:Inspect the lock actuators, wiring connections, and door lock switches for any defects or damage.
  • Mirror Adjustment Problems:Examine the mirror control switch, wiring harness, and mirror motors for potential issues.

By following a logical troubleshooting process, identifying and resolving body electrical faults can be achieved efficiently, restoring the proper functioning of these components.

Audio System

The audio system in the HZ Holden consists of a radio, speakers, and other components that work together to provide sound for entertainment and information.

The radio is the central component of the audio system and receives audio signals from various sources, such as AM/FM radio stations, CDs, or USB drives. The radio then amplifies the audio signals and sends them to the speakers.


The speakers convert the amplified audio signals into sound waves that can be heard by the listener. The HZ Holden typically has four speakers, two mounted in the front doors and two mounted in the rear parcel shelf.

Other Audio Components

In addition to the radio and speakers, the audio system may also include other components, such as an amplifier, equalizer, or subwoofer. These components can enhance the sound quality or provide additional features, such as increased bass response.

Common Audio System Faults and Troubleshooting

Common audio system faults include:

  • No sound from the speakers
  • Distorted sound
  • Intermittent sound
  • Radio does not turn on

Troubleshooting audio system faults can be done by checking the following:

  • Check the fuses for the audio system
  • Check the connections between the radio and the speakers
  • Check the speakers for damage
  • Check the radio for damage

Security System

The security system in the HZ Holden is designed to deter theft and unauthorized entry. It consists of an alarm, immobilizer, and other security features that work together to protect the vehicle.

The alarm is triggered when a door, window, or trunk is opened without the key being used. It will also sound if the vehicle is moved without the key being in the ignition.


The immobilizer is a device that prevents the engine from starting without the correct key. It works by disabling the fuel pump and ignition system when the key is not present.

Other Security Features

Other security features include a remote keyless entry system, a panic button, and a tilt sensor. The remote keyless entry system allows the doors to be locked and unlocked without using the key. The panic button sounds the alarm when pressed, even if the alarm is not armed.

The tilt sensor triggers the alarm if the vehicle is tilted or moved.

Common Security System Faults and Troubleshooting Procedures

Some common security system faults include:

  • The alarm is not sounding when it should.
  • The immobilizer is not preventing the engine from starting.
  • The remote keyless entry system is not working.

These faults can be caused by a variety of factors, including:

  • A faulty sensor.
  • A loose connection.
  • A damaged component.

If you are experiencing any security system faults, it is important to have the system checked by a qualified technician.

General Inquiries

What are the common electrical faults in HZ Holdens?

Common electrical faults in HZ Holdens include issues with the charging system, ignition system, lighting system, and body electrical components. These faults can manifest as problems with starting the vehicle, flickering lights, or malfunctioning electrical accessories.

How do I troubleshoot electrical problems using the wiring diagram?

To troubleshoot electrical problems using the wiring diagram, identify the affected circuit and trace the wires to locate the source of the issue. Check for loose connections, damaged wires, or faulty components. Refer to the diagram to understand the component connections and voltage readings.

Can I make modifications to the electrical system using the wiring diagram?

While the wiring diagram provides a comprehensive overview of the electrical system, it is not recommended to make modifications without proper knowledge and experience. Altering the electrical system can compromise its integrity and safety. Consult a qualified mechanic for any modifications or upgrades.

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