The Electrical Auto Systems On Your Car

Electrical Auto Systems Overview

Electrical Auto SystemsThe electrical auto systems in a motor vehicle are ones that provide the electrical energy to crank the engine for starting, recharge the battery after cranking, create the high-voltage sparks to fire the compressed air-fuel charges, and power the headlamps, light bulbs, and electrical auto accessories.

Electrical auto systems include the battery, wiring, lights and lighting systems, wiper system, starting motor and controls, alternator and voltage regulator, electronic ignition, and electronic fuel metering, electronic fuel injection systems, computerized electronic engine control system, engine management system, an electronically displayed driver information system, various types of radios and sound systems, and many other electrically operated and electronically controlled systems and devices.

Some examples and information on certain electrical auto systems is listed below:


The battery stores electricity and supplies current to the car’s electrical system when needed. The alternator/generator would normally fulfil this need when the engine is running but there are occasions when the power is needed and the engine is not running.


One of the major foundation components of the vehicles electrical auto systems. In older cars they used to have a generator, sometimes called the dynamo, but all modern cars have an alternator – a more efficient way of charging the battery. A fanbelt drives the alternator and it doesn’t generate electricity until the engine is running. This electricity is then sent to recharge the battery and feed current to the electrical system.

Starter Motor

The starter motor is a small electric motor fitted with a gear, This gear is called a pinion and it engages with teeth on the flywheel (ring gear) and turns the crankshaft. When the ignition key is turned to the start position, the starter motor solenoid is engaged and current is drawn from the battery. This causes the starter motor to turn and engages the pinion with the ring gear. When the engine starts turning faster than the starter motor, the pinion disengages.

Ignition Switch

The ignition switch directs the current to the ignition system, the starter motor solenoid and the fuse box to feed the various accessories.

Instruments & Gauges

All cars have a selection of instruments and gauges.

  • Every car has a speedometer, which can be operated by a cable from the transmission or wheels, or can be electrically operated by a transducer from the transmission.
  • A variable resistor in the fuel tank, which is attached to a float, operates the fuel gauge and provides an indication of the fuel level.
  • The temperature gauge is mounted in the instrument cluster and is operated by a sending unit mounted in a water jacket in the cylinder head.
  • The instrument cluster also contains warning lights for various electrical systems.
  • Most lights work on the principle that when the circuit is inoperative the light is on.


The electrical current that operates the lights is drawn from the alternator when the engine is running, and the battery when the engine is running too slow for the alternator to produce enough current, or the engine is stopped.

  • Most of the light globes have a single filament like a house globe, which heats up and glows when current is applied.
  • However there are some exceptions; most headlamp globes have two filaments, which heat at different rates.
  • The main beam glows brighter than the dipped beam.
  • The brake light and rear parking light are often incorporated into the same globe. This globe also has two filaments.
  • The indicators are operated through a flasher unit, which quickly switches on and off the current to the globes.
  • A switch that is attached to the brake pedal operates the brake light.
  • When the pedal is depressed the switch comes on and operates the lights, when the pedal is released the switch turns off.


The wipers are operated by a small electric motor. When the wipers are switched on, current is sent to the motor and this moves a set of linkages, which are attached to the wiper arms. Different wiper speeds are achieved by varying the voltage to the wiper motor.


Wiring distributes the current from the battery to all the electrical auto components. It also carries signals from sensors and switches.


Fuses protect the wiring; they form a bridge in the electrical auto circuit. If the circuit overloads for any reason the fuse will blow and break the circuit.


There are many accessories on modern cars that are operated by the electrical auto system.

Need Help?

Should there be any issues with your electrical auto systems, it is best to have an auto electrician attend and check the electrical auto components and systems as required. 

ACE Auto Electrician come to you 7 days a week to attend to you and your vehicle offering you protection and peace of mind with our nationwide 12 month - 20,000km warranty.

CONTACT US ON 1800 ACE AUTO (1800 223 288)

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