Introduction
Restoring a classic car can be an extremely rewarding experience. However, rewiring a classic car presents unique challenges compared to more modern vehicles. Electrical systems in classic cars can be complex and intimidating. But with some basic knowledge, patience, and the right tools, I successfully rewired my 1965 Ford Mustang coupe and finally got the lights working again. In this article, I will walk through the complete process to help fellow classic car enthusiasts rewire their own vehicles.
Why Rewiring is Necessary
There are several reasons why rewiring your classic car may be necessary:
- Original wires degraded - Insulation breaks down over decades, exposing copper that can short and cause fires. Replacing old wiring reduces risk.
- Previous improper modifications - Haphazard additions or changes to wiring by previous owners often needs redoing.
- Converting from 6 volts to 12 volts - Many classics used 6V systems. Upgrading to 12V requires rewiring.
- Adding new electronics - Modern ignition, stereo, or other electronics may require new wiring.
- Nothing works anymore - Over time, electrical gremlins develop. Rewiring provides an opportunity to start fresh.
I decided to do a complete rewire of my Mustang because the original wiring was deteriorated and I wanted to upgrade from 6V to a more modern 12V system. Additionally, the previous owner made some improper modifications that caused nothing to work correctly.
Planning the Rewire
Careful planning is crucial before beginning to rewire your classic car. Rushing into it without preparation will only lead to frustration. Key steps in planning the rewire include:
- Reviewing wiring diagrams - Obtain diagrams for your specific make and model. These show how everything should connect.
- Taking inventory - Note what electrical components are in the car and will need connecting.
- Designing a logical layout - Plan where to route wires and position components.
- Selecting wire gauge/type - Choose the proper gauge and insulation type for each circuit.
- Making a parts list - Order what you'll need ahead of time to avoid delays.
I spent several weekends poring over wiring diagrams and planning every detail of the rewire before buying parts and picking up my tools.
Selecting the Right Wire
Using the correct type and gauge of wire is critical for proper functioning and safety of your vehicle's electrical system. Here are some guidelines for selecting wire:
- Gauge - Heavier gauge (thicker) wire is needed for high amperage circuits. Lighter gauge for lower amps.
- Insulation type - Use high quality insulation suited for automotive use, such as cross-link polyethylene.
- Circuit runs - Longer wire runs may require heavier gauge to minimize voltage drop.
- Compatibility - Ensure copper wire is compatible with your terminals and connectors.
- Cost - Buy quality wire, but don't overspend on unnecessary extras.
I selected 16 gauge cross-link polyethylene wire for most circuits in my Mustang rewire, along with heavier 10 gauge for the starter motor circuit which draws higher amps. Pre-terminated weatherproof connectors made installation much easier.
Helpful Rewiring Tips
Here are some helpful tips I learned through my rewiring experience:
- Take photos - Document how everything is originally wired just in case.
- Label everything - Use wire labels and a schematic to note wire routing for future reference.
- Solder connections - Soldering makes solid, weatherproof connections versus crimping.
- Use grommets - Protect wires from abrasion when passing through metal by installing rubber grommets.
- Think logically - Route wires cleanly and how you'd expect, not haphazardly.
- Work methodically - Focus on one circuit at a time for organization.
- Install protection - Use fuses or circuit breakers to protect from shorts and overload.
- Allow slack - Leave a little extra wire length to make connections easier.
- Secure wires - Use zip ties and insulation tape to prevent wires shifting or rubbing.
Taking it slow and methodical, using labels, and following my wiring diagrams precisely led to rewire success without any major issues.
Troubleshooting Electrical Problems
Despite the most careful planning and installation, electrical gremlins can still pop up. Here is how to troubleshoot some common problems:
Lights not working:
- Check for power at the switch. If none, trace wiring back to find the open.
- Verify ground connections are solid.
- Check for blown fuses.
- Ensure proper bulb wattage is installed.
Gauges or accessories inoperative:
- Use a test light to check for power at device.
- Check for loose or disconnected wires.
- Test ground connections with an ohm meter for continuity.
- Wiggle wiring while observing gauge to find intermittent shorts.
Dim lights:
- Wire gauge may be too small - replace with heavier gauge wire.
- Poor ground connection - inspect grounds at frame and battery.
- Alternator not charging - test alternator voltage output.
For anything beyond basic troubleshooting, a wiring diagram and voltmeter are indispensable for diagnosing problems. Having spare fuses, wires, and common spare parts makes troubleshooting much simpler.
Completing the Rewire and Seeing Those Lights
After many long weekends crawling under the Mustang's dash rewiring the ignition, instruments, fusebox, and lighting circuits, the moment of truth finally arrived. I turned the key, said a prayer, and the engine roared to life! All the gauges worked,warning buzzers buzzed, and most importantly - the headlights lit up brightly. That first successful test drive with everything working was an amazing feeling after all the effort invested.
While rewiring a classic car requires research, planning, and patience, the end results are incredibly rewarding. The feeling of accomplishment breathing new life into a classic by rewiring it yourself cannot be matched. I encourage all enthusiasts to grab some tools and upgrade their car's old electrical system. That first time those headlights blaze down the road after a complete rewire makes all the work worthwhile.