Find parts for your car
Makes
- (-) Remove Audi filter Audi
- Alfa Romeo (4) Apply Alfa Romeo filter
- BMW (5) Apply BMW filter
- Citroen (11) Apply Citroen filter
- Fiat (4) Apply Fiat filter
- Ford (25) Apply Ford filter
- Honda (10) Apply Honda filter
- Hyundai (12) Apply Hyundai filter
- Jaguar (10) Apply Jaguar filter
- Kia (5) Apply Kia filter
- Land Rover (7) Apply Land Rover filter
- Mazda (7) Apply Mazda filter
- Nissan (5) Apply Nissan filter
- Peugeot (20) Apply Peugeot filter
- Renault (13) Apply Renault filter
- Suzuki (6) Apply Suzuki filter
- Toyota (6) Apply Toyota filter
- Vauxhall (17) Apply Vauxhall filter
- Volkswagen (11) Apply Volkswagen filter
- Volvo (8) Apply Volvo filter
Parts
- (-) Remove Axle filter Axle
- (-) Remove Bonnet filter Bonnet
- (-) Remove Bumper filter Bumper
- Battery (19) Apply Battery filter
- Dashboard (11) Apply Dashboard filter
- Door (24) Apply Door filter
- Door Card (2) Apply Door Card filter
- ECU (1) Apply ECU filter
- ECU Engine (1) Apply ECU Engine filter
- Fuse Box (80) Apply Fuse Box filter
- Glow Plug (1) Apply Glow Plug filter
- Glow Plug Relay (1) Apply Glow Plug Relay filter
- Headlight (1) Apply Headlight filter
- Injector (1) Apply Injector filter
- Parking Sensor (2) Apply Parking Sensor filter
- Parking Sensors (1) Apply Parking Sensors filter
- Seat (3) Apply Seat filter
- Tailgate (2) Apply Tailgate filter
- Trim (2) Apply Trim filter
- Window Motor (2) Apply Window Motor filter
- Wiper Motor (1) Apply Wiper Motor filter
- Wiring Loom (47) Apply Wiring Loom filter
Getting into the details of the electrical system
The electrical systems on most modern cars consist of negative earth circuits. The main power source is the 12 volt battery and when the engine is running, the alternator. The systems run off a positive flow with a negative earth return through the body of the vehicle. On some older vehicles the system is run on a positive earth, but this is mainly on 6 volt systems.
A set of wiring looms, which is all the cables bound together which run through the vehicle and branch of where power is needed for individual components. In addition there is a heavier cable running the main charging, ignition and the starter motor to supply the high voltage required to turn and start the engine and keep the battery charged. The wiring for all the circuits in the car are of different thickness and amperage depending on the components power requirements. The wires are colour coded to enable tracing wires when looking for a fault. On modern cars with electronic control devices and components, printed circuits are widely used as they take up less space than a bunch of wires. The power source for the electrical systems is switched on via the ignition key/switch apart from the lighting system which is on a live feed to enable the lights to be used for parking. This ensures that the battery will not be run down when the car is left unattended.
The power source runs through a fuse box and relays, which protects components from damage due to electrical short outs. Apart from the starter motor most components run on 5 amp. 10 amp, 15 amp, 20 amp, 25 amp and 30 amp wiring and are fused according to the power requirements being carried on each wire. Components are activated through the ignition, relays and switches and with remote controlled devices through electromagnetic switches.
What if something goes wrong with the electrical system?
The most common faults with the electrical system involve the lighting system of the vehicle requiring the replacement of blown bulbs. In the event of a malfunction of any component, the fuses should be checked in the fuse box, normally located in the front footwells or glove compartment. This box has a labelled colour coded fuse array and individual fuses can be visually checked to see if it has blown. This serves as a starting point to resolving electrical faults.