1957 Chevy Wiring Harness - Super Chevy Magazine

The Painless kit comes in a nice, neat bundle, and includes pretty much everything you need for installation except for crimpers and wire cutters. It's always good, though, to have some extra electrical terminals, tape, and shrink tubing handy.

The Painless kit comes in a nice, neat bundle, and includes pretty much everything you nee

Thanks to the aftermarket, you can equip your classic Chevy with all sorts of modern performance and luxury items that'll make an old car feel like a newer one. From modern fuel injection, to power windows, to high-tech stereo systems, pretty much any option you can find on a new car, you can install on an old one.

The problem is, the old factory wiring harnesses of the classic cars were never meant to handle the electrical load of modern accessories, or the sheer number of them. It's the same thing as having 12 different appliances in your kitchen, but only one outlet to plug them into. Even if you add ways to plug more accessories into your original wiring harness, it won't be long before the electrical load of all the modern equipment will melt the factory harness, and possibly turn the car into a fireball.

But the same aftermarket that's brought you all the high tech stuff to equip your Chevy also has the solution, a modern wiring harness capable of handling just about anything, with plenty of accessory hookups so you can customize and equip your old car with anything you're thinking about.

To make the job easier, both the front and rear seats were removed from the car. The back seat must come out so you can access the wiring going to the trunk.

To make the job easier, both the front and rear seats were removed from the car. The back

Our project '57 was a prime candidate for an improved, 21st century wiring harness. After having a Classic Instruments gauge upgrade, an MSD-6 ignition box, and electric fans added, the factory '57 wiring harness (although fairly new from the car's earlier restoration) couldn't handle the power windows and stereo upgrades the car was slated for. So, we called the electrical gurus at Painless Performance to get one of their Tri-Five 18-circuit wiring harness kits.

A few weeks later, Painless founder Dennis Overholser showed up at our door with the kit we needed and his tools to help us install the harness. Dennis founded Painless Performance in 1990 (then Perfect Performance Products) to handle the needs of street rodders who were installing modern parts on older cars looking for a reliable wiring harness that was easy to install. From there the company took off, becoming one of the leading suppliers of aftermarket harnesses to the hobby.

Dennis took one look at the sorry state of the wiring in our '57, and knew he had his work cut out for him. Follow along as we upgrade the wiring in our hardtop.

Even though it's obvious, some people do forget to unhook the battery before doing wiring work. That's when bad things happen. Make sure both cables are disconnected from the battery and well away from the terminals. Sometimes it's best to remove the battery entirely to be safe.
Even though it's obvious, some people do forget to unhook the battery before doing wiring
With the seats out, it was time to start removing parts of the dash to get at the old harness. On a Tri-Five, the emergency brake handle has to be disconnected so it can be moved out of the way, along with the bottom cover plate on the steering column, and the kick panel covers.
With the seats out, it was time to start removing parts of the dash to get at the old harn
This was just part of the rat's nest wiring cluster we found underneath the dash. While these wires on their own weren't bad, together in this combo, they made for an unsightly mess that was loaded with danger, and made it nearly impossible to add any other electrical accessories to the harness.
This was just part of the rat's nest wiring cluster we found underneath the dash. While th

In the back, the rear armrest has to come out, since the wiring going to the trunk runs along the front part of the inner wheelwell. While you've got the interior disassembled, it's not a bad idea to look at installing some sound deadening material, and cleaning out the small areas where junk and gunk can accumulate for over 50 years since the car was built.
In the back, the rear armrest has to come out, since the wiring going to the trunk runs al
Back up front, the factory air controls are removed, too. Our '57 has a Classic Auto Air A/C system installed, but the Painless harness will hook up to any A/C system.
Back up front, the factory air controls are removed, too. Our '57 has a Classic Auto Air A
Next up was removing the gauge cluster. On a '57, it's four screws and out she comes.