How to Rewire Your Classic Car Like a Pro and Impress All Your Friends

Introduction

Rewiring a classic car can be an intimidating task, but with some planning, patience and the right tools, I was able to rewire my 1965 Mustang and impress all my friends. In this article, I will walk through the entire process I followed to successfully rewire my classic car, from developing a plan to splicing wires. I will also share tips on choosing the right wiring kit, safety considerations, troubleshooting common problems, and testing the system. Whether you're a novice or a seasoned grease monkey, you'll gain the confidence to rewire your own classic ride after reading this.

Develop a Wiring Diagram

The first step is to develop a complete wiring diagram. This will be your roadmap for the rewiring project.

• Obtain a factory wiring diagram for your specific make and model. This shows how the car was originally wired from the factory.

• Decide on any customizations you plan to make, like adding a modern radio or electronic ignition. Diagram these separately.

• Get a wiring diagram for any aftermarket accessories you plan to install like gauges or power windows.

• Using pen and paper, compile all these diagrams into a master wiring blueprint. It should show all circuits, fuse locations, wire sizes and colors.

• Make copies to reference during the actual wiring work. Highlight each circuit as it's completed.

Choose a Wiring Kit

With my master wiring diagram complete, next I chose an aftermarket wiring kit specifically made for my Mustang's year and model.

• Kits contain all new wires, terminals, fuses, switches and supplements you'll need. Better than splicing into old, cracked wires.

• Buy the most complete kit you can find for your car. I spent extra for one with all new switches and a new fuse box.

• Carefully review what's included versus your diagram. Order any missing adapters, accessories or wire separately.

• Optional expandability kits let you integrate modern electronics down the road.

Safety First!

Anytime you're dealing with your car's electrical system, there are some important safety considerations:

• Wear protective eyewear when splicing wires to guard against stray strands.

• Disconnect the battery at the beginning of the project to avoid shocks, sparks and system damage.

• Never join wires without adequately insulating connections, for example with heat shrink tubing. Exposed metal can cause shorts.

• Take your time and follow wiring diagrams closely to avoid polarity mistakes that can ruin electronics.

• Keep a fire extinguisher nearby, just in case of any automotive electrical fires.

• Allow no loose wires to dangle freely under the dash. This presents a real fire hazard.

Remove Old Wiring

With safety gear on and battery disconnected, now the real fun starts - ripping out the old wiring!

• Label each wire as you disconnect it. Masking tape and a marker are perfect for this.

• Cut wires using wire cutters or snips. Don't just pull them out as this can damage connectors.

• Remove any mounts, tape or clips holding wires in place. The new kit will include new fastener hardware.

• Draw a rough diagram showing wire routing through fins, holes and grommets. Replicating this with new wiring makes life easier.

• Inspect wires as you remove them. Cracked, frayed or burned insulation indicates trouble areas to address.

• Pay attention to ground wires. Often the bare metal itself acts as a grounded surface.

Install New Wiring

Here are some tips for cleanly installing the new wiring kit:

• Route wires exactly as the old ones came out. Follow any diagrams you made. Reuse existing holes and channels.

• Anchor wires every 6-8 inches using clips provided. Don't allow wires to rub against sharp metal edges.

• Neatly bundle and tie wires that run together, like with zip ties or electrical tape. Prevent rubbing and chafing.

• Double check terminals to confirm wires go to the proper pins and connectors according to your diagram.

• Slide heat shrink tubing over wire joints and use a heat gun to seal moisture out of connections.

• Avoid overheating wires or melting insulation.

• Confirm all unused wires are adequately capped off so they don't short against the body. Tape ends for extra protection.

Reconnect Battery and Test Systems

With all new wires cleanly installed, it's time to fire things up!

• Reconnect battery and install new fuses of proper amperage based on your diagrams.

• Turn the key to test all systems one by one - lights, signals, ignition, gauges, etc.

• Expect some issues the first go around. Check for loose connectors, blown fuses, or polarity reversals.

• Address any problems, then methodically test each circuit again until all are working properly. Grab a beer, you earned it!

Troubleshooting Common Problems

Despite the most careful planning, issues can still crop up. Here are some common new wiring bugs and how to squash them:

• Shorts: New insulation chafing or exposed wires grounding out. Inspect all routing.

• Opens: Wires disconnected or corroded terminals. Wiggle test every connection.

• Polarity: Swapped positive and negative. Double check with diagrams.

• Crossed Circuits: When signals cross to the wrong component. Check terminals closely.

• Voltage Spikes: Caused by unmatched loads. Install suppression diode on ignition coil.

• Light Flickering: Poor grounds, loose connections, or failing alternator or regulator.

Impress Your Buddies!

When all troubleshooting is done and your new wiring job works flawlessly, it's time to show off your handiwork!

• Host a cruise-in and open the hood to display your masterpiece.

• Discuss your project and offer advice to others thinking of rewiring.

• Confidently repair minor electrical issues that inevitably crop up, thanks to your knowledge.

• Install cool new accessories like a bluetooth stereo system. Friends will be impressed!

• Bask in the satisfaction of overcoming an intimidating project and improving your ride.

Rewiring your classic car is a major undertaking but exceptionally rewarding. Hopefully this overview gives you confidence to tackle this project yourself. Take it slow, be safe, and soon you'll be impressing all your buddies with your restored ride's flawless wiring job!