Modified Mustangs & FordsHow To Interior Electrical
Vintage Ford Electrical System Renovation
Upgrade Your Ford's Central Nervous System
Whether you're restoring or restomodding an old Ford, the electrical system requirements are pretty much the same. You need safety and reliability from bumper to bumper because an electrical system is only as reliable as its weakest link. When it comes to automotive electricity, there are no legitimate shortcuts (no pun intended). This is where great attention to detail brings peace of mind.
For most projects, we recommend complete replacement of all electrical system components, including the wiring, if the vehicle has never been restored before. Wiring becomes unsafe because the insulation gets dry and brittle and connectors become corroded. Dry insulation cracks, sometimes causing the copper or aluminum wiring to become exposed to the elements. Exposed wiring can short to ground, starting an electrical system fire if the fuse doesn't blow first.
Corroded connectors cause problems because they create high electrical resistance and heat, which can cause a malfunction or fire. A faulty ground will also cause a variety of odd electrical system gremlins. In the pages ahead, we show you how to plan and properly upgrade your Ford's electrical system, which results in great performance and peace of mind.
Stock or Aftermarket?
When we were planning our '65 Mustang 5.0L EFI coupe project, we looked at our electrical system options. We could go aftermarket, such as a Painless Wiring or Ron Francis wiring system, and go custom all the way. But we wanted simplicity--a bolt-on, plug-in wiring system that would be easy to install. We looked to Virginia Classic Mustang for electrifying answers. Because we're building a restomod with 5.0L EFI power, Virginia Classic Mustang's Brant Halterman suggested the use of '66 Mustang electrics. That model year incorporates running changes that make it better than '64-1/2 and '65. It is also quite compatible with the five-dial instrument panel we had planned for Ed. Halterman set us up with 100 percent of the original factory wiring available--the main underdash loom, all underhood wiring harnesses, a taillight harness, and all the switches and electrical components necessary to power the accessories.
What you may find discouraging is the cost of a complete rewiring. It is not cheap. But, when you compare this cost to the cost of vehicle replacement if there's a fire, new wiring and switches are cheap. You can completely rewire your classic Mustang for far less than $1,000 and never have to worry about it again, because the expected life span of wiring is at least 30 years.
When you rewire to stock condition, always go Ford one better on attention to detail. Closely examine where wiring can chafe due to road vibration. Then generously wrap the harness with electrical tape or plastic in that area only, to reduce the risk of a rub-through. Connections exposed to the elements and corrosion should be sealed for protection.
We suggest replacement of switches, because contacts do wear out. High-amperage applications, such as headlight and air conditioning compressor clutch switches, should always be replaced. Ford headlight switches are notorious for circuit-breaker failure, which will leave you in the dark unexpectedly. A failed headlamp switch circuit breaker will make the headlamps flash off and on. Automotive circuit breakers cannot be reset manually either. They reset themselves when the breaker contacts cool. Other shaky spots are the turn signal switch and plug. These switches like to short circuit behind the steering wheel and billow smoke from the steering column. When in doubt, throw it out.
Doing It Yourself
Doing it yourself means looking to the aftermarket for answers. Painless Wiring and Ron Francis Wire Works are two excellent sources for wire-it-yourself electrical systems for street rods, hot rods, and restomods.
Painless Wiring offers the car builder an outstanding wiring system (PN 10102) that includes an original equipment-style fuse box that installs under the dashboard. Wires are color-coded and circuit-specific. You simply route each wire or wires to the circuit you want to energize. Painless Wiring offers thermal cross-linked, high-temperature wire, which means it doesn't kink, endures chafing, and can stand up to 275 degrees F. Painless gives you all the wire you will ever need, terminating at the fuse box. Each Painless harness includes a bulkhead connector or bracket for ease of use. The basic Painless system includes provisions for air conditioning and heat, brake lights, an ignition coil, an electric fan, emergency flashers, gauges, lights, a horn, turn signals, wipers, dome lights, and even a third brake light. Painless also offers switches and other accessories to complement its wiring systems.
Painless Wiring's Cirkit BOSS allows you to install mini-circuits for a special application such as a high-power sound system, additional lighting, or an electronic fuel pump. We opt for Painless Wiring's Brake Light Relay Kit (PN 30105) in our T-bird taillight conversion article, which begins on page 76. Ron Francis Wire Works offers a custom wiring harness that enables you to wire your electrical system without limitation. The Ron Francis system includes a fuse box with two turn signal flashers, a relay, a resistor, and a host of other nice features. All you have to do is plug in each circuit, and you're ready for business.