How to Do Your Own Automotive Wiring Without Formal Training

Doing your own automotive wiring can be daunting without formal training, but with some research and preparation, it is possible for a dedicated DIYer to learn. Here is a comprehensive guide to teach you the basics of automotive electrical systems and how to complete common wiring jobs safely and properly.

Understanding Automotive Electrical Systems

The first step is developing a solid understanding of how automotive electrical systems work. Here are the key concepts to learn:

Electrical circuits - Automotive wiring involves creating circuits to power devices and components. Circuits require a power source, load, and complete loop back to the source.
Common automotive circuits - Basic systems found in all vehicles include charging, starting, ignition, lighting, accessories, and computer/sensors.
Wire gauges - Wires come in different thickness called gauges. Thicker wires can handle more current. Match wire gauge to the amperage of the circuit.
Fuses and relays - Fuses and relays protect electrical circuits and components. Fuses blow to "open" a circuit if current exceeds the rated amperage. Relays control high current with lower current signals.
Routing wires - Wires must be properly routed to avoid heat/friction damage, away from moving parts, and secured neatly. Follow factory routing if possible.
Electrical safety - Working with automotive electricity poses shock hazards. Use extreme caution and proper safety gear. Tips include disconnecting the battery, avoiding hot wires, and working one circuit at a time.

Gathering the Right Supplies

Completing wiring jobs yourself requires having the proper tools and materials:

Wiring diagrams - Accurate wiring diagrams for your specific vehicle are essential to have on hand for reference. Factory service manuals provide diagrams for each circuit.
Wire strippers - A wire stripper allows you to neatly strip insulation off wires without damaging the copper strands. Self-adjusting strippers are very handy.
Crimpers and connectors - Crimpers securely attach connectors and terminals to wires. Heat shrink tubing also protects connections.
Test light and multimeter - Use a test light or multimeter to check wiring continuity, isolate faults, and confirm proper operation.
Cable ties and loom - Neatly bundle and route wires using cable ties and flexible wire loom. Avoid loose hanging wires.
Heat gun - A heat gun allows you to shrink heat shrink tubing for waterproof wire connections. It can also help soften adhesive lined loom when wrapping bundles.
Soldering iron - Optional for very robust permanent splices. Requires heat shrink or electrical tape over all soldered splices.

Key Automotive Wiring Procedures

With the right understanding and supplies, you can tackle many common wiring projects:

Installing New Circuits

Carefully plan the wire size, route and connections based on amperage needs and the fuse providing protection.
Mount new circuits like lights and switches in appropriate locations.
Run wires neatly along factory routes in the vehicle, properly supporting and isolating wires.
Use grommets when running wires through metal panels to avoid fraying.
Make high quality crimped or soldered connections and cover with heat shrink.
Confirm proper wiring before connecting directly to vehicle circuits.

Repairing Damaged/Corroded Wires

Identify damage causes like rubbing, corrosion, overheating, or shorting.
Locate damaged wiring segments and splice in new wire using crimped or soldered connectors.
Protect splices with heat shrink tubing.
Wrap wires with new loom if insulation damage is extensive.

Diagnosing Electrical Problems

Use wiring diagrams to follow circuits and locate components.
Check for power at fuse, then work your way through the circuit.
Isolate faults like shorts/opens using a test light or multimeter.
Inspect connections for corrosion, damage, or high resistance.

Modifying Existing Circuits

Locate where you need to tap into an existing circuit based on wiring diagrams.
Disconnect the battery before splicing into any circuit.
Tap into factory wires with crimped or soldered connections and heat shrink.
Avoid voltage drops by keeping splice lengths short.

Practicing on Junkyards Cars

Before tackling critical wiring on your daily driver, get hands-on practice on junkyard cars. This allows you to:

Learn to identify wiring colors/gauges and terminals.
Practice proper crimping and splicing techniques.
Simulate common procedures like adding a new light circuit.
Troubleshoot electrical issues on a "broken" vehicle.
Make mistakes without worrying about damaging your vehicle.

Staying Safe

Always prioritize safety when working on vehicle wiring as a beginner:

Disconnect battery - Always disconnect the battery before beginning any work.
Wear insulated gloves - Use thick rubber insulated gloves when handling wires.
No hot swaps - Never remove or install wiring with the system powered up.
One circuit at a time - Focus on fully completing one circuit before moving to another.
Use a helper - Have someone assist you for safety and extra hands when needed.
Know your limits - Do not attempt very complex electronics like ECU sensors or modules.

The key to successful DIY automotive wiring is taking the time to properly understand electrical systems, get the right tools, practice procedures, and put safety first. Pay close attention to details on every wiring job. Over time you can acquire the knowledge and experience to take on more challenging wiring projects.