Replacing The Main Underdash Electrical Harness On A 1966 Ford Mustang – San Diego, California

     My mobile business takes me to different places every day. Sometimes I work outside, and enjoy the sunny fresh air. Today, was cold and very wet, so it was good to work inside. I just finished the second phase of a complete electrical replacement on a 1966 Ford Mustang by replacing all the under dash electrical. The first phase was all the under hood electrical and headlights. The customer had issues with an intermittent no-start and charging problem. When I first inspected the electrical system, the Mustang would start fine directly from the starter solenoid, but only sometime at the ignition switch. There were previous splices all over the electrical harness, and the ignition switch had been patched together after being stolen years ago. The wires were too brittle to be repaired, and I’m pretty strict on not repairing 40 plus year old wiring anyways.

     As I pulled the old under dash electrical harness out of the dash, it made crackling sounds as I was trying to bend it out of the dash. It was old and petrified. After I pulled out the harness, I removed the rest of the old alarm system that was wired throughout the car. The old alarm system was a part of the electrical issues. It was not installed very well, and seemed to be attached to everything. I also removed the old 80’s style tape deck radio, and it will be later replaced with a stock appearing modern radio from Custom Autosound. Whenever I replace electrical, I replace all the related switches. If the windshield wiper switch is still working, it is not necessary to replace it. They don’t get used as often. The ignition is always a must. They cost under $10, and when they fail, it can damage the harness, and leave you stranded. The headlight switch is the second most important switch to replace. It controls your headlights, interior lights, gauge lights, and sends power to the rear lights. When the switch gets corroded, it causes lights to flicker, and they get overheated too.

     The last phase will be replacing the rear tail light harness, and installing the new radio. Afterwards, the customer wants to start focusing on the cosmetics. Over the years, I’ve worked on a lot of nice looking cars, but only to find hidden issues. The best way to restores an old classic, is from the inside out.

If your having electrical problems with your Classic Car, then give Classic Resto Garage a call at a 619-929-8506, or fill the contact form.

Happy Cruising!

posted by inlinesix in 65-66 Mustang and have No Comments