Car Wiring Color Codes
Look up common automotive wire colors and their typical circuit functions — a quick reference for diagnostics and accessory installation.
Wiring Color Reference
Select color → function + notes
How It Works
Automotive wiring colors follow loose conventions that vary by manufacturer and region, but common patterns exist — especially for ground, power, and audio circuits. Always verify with the specific vehicle’s wiring diagram.
How to Use This Calculator
- Identify the wire color you need to trace or connect.
- Select it from the dropdown.
- Review the typical function and any important notes.
- Verify against the vehicle-specific wiring diagram before making any connections.
- For critical circuits (airbag, ABS), always use a factory wiring diagram.
Worked Example
Reference Table
| Color | Common Function | Important Note |
|---|---|---|
| Red | Constant 12V + | Always live — fuse before tapping |
| Black | Ground | Return path — use proper earth point |
| Yellow | Ignition / accessory | 12V with key on only |
| Orange | Illumination | Dims with headlights |
| Blue | Remote turn-on / reverse | Amplifier turn-on in car audio |
| Green | Turn signal | Verify right vs left for your brand |
| Purple | Speaker wires | Audio wiring convention |
| Brown | Tail light / ground | Rear lighting circuit |
Frequently Asked Questions
Are wire colors standardized across all car brands?
Not fully. ISO 6409 and similar standards provide guidance, but manufacturers often deviate. Japanese (Toyota, Honda) and German (VW, BMW) manufacturers each have their own internal conventions. Always use a vehicle-specific wiring diagram for critical work.
Why is black used for ground instead of a negative symbol?
Black for negative/ground is an automotive convention (and also electronics convention). In 12V automotive systems, the negative terminal is chassis-grounded, and black wires connect components back to that common ground.
Can the same color wire have different functions in the same car?
Yes — harness connectors and looms may reuse colors for different circuits in different areas of the car. Wire colors alone are not sufficient for identification without the pin location and connector reference from the wiring diagram.
What are the risks of incorrectly identifying a wire by color?
Incorrect identification can cause short circuits, blown fuses, non-functioning components, or in worst cases, fires or airbag deployment. Always test with a multimeter (voltage, continuity) rather than relying solely on color.
