Video: Bad Wiring – What Not To Do With Holley Performance

Warning: For your own safety, always disconnect the battery or main power supply of your vehicle before starting any electrical work.

Electrical wiring is one of those tasks where arguably the most important skill to have is patience. At one time or another, just about every automotive enthusiast has found themselves on the wrong side of a bad wiring job, whether by their own hand or that of the previous owner. We’ve all been there; the car won’t start, a component lost power, or a controller lost communication with a sensor. So your body ends up contorted in an awkward position, with your hands and arms buried in a rats’ nest of single colored wires behind the dash or in the engine bay.

Not only can a poor wiring job do much more than simply leave your component without power — it can fry your expensive electronics, permanently damaging them; excessive noise can cause a signal to drop or read inaccurately; or even worse, watching that car you poured blood, sweat, and tears into burn to the ground from an electrical fire. It’s happened before, and it will happen again.

From corroded battery terminals and exposed wires, to wire nuts and household wiring – Holley displays many of the most common wiring mistakes on one board.

In an effort to save as many enthusiasts the headaches associated with bad wiring mistakes, Tom Kise of Holley Performance Products created the video above to point out the most common wiring mistakes made when setting up a new component. This video will save you the hassle of having to fix your own wiring mistakes by doing it right the first time and will expedite the process of correcting a wiring issue that was no fault of your own.

Not All Wire Was Created Equal

The first common mistake that Kise points out is the peculiar belief that some have thinking that all electrical wiring is the same. Depending on its intended use, the insulation of the wiring may be thicker, it might be chemical resistant, and/or rated for high temperatures.

Opening up the hood of a car and finding bundles of Romex solid core household wiring snaking through the engine bay should be worrying. Romex wiring was designed to be run through conduit in the wall of a home or office, which is a much more stable environment than sitting under the hood — where engine bay temperatures can easily exceed 200+ degrees F at the track, while potentially being splashed with fluids like fuel, oil and coolant. It’s pretty easy to assume what could happen next.

Crimping Your Style

Never use household wire nuts as a substitution for a proper crimp-style wire connector or soldering - its intended design poses a safety hazard in automotive wiring (left). Temperature control is very important for a secure connection all the way through the wire, so Kise recommends against ever using a torch instead of a properly rated soldering iron.

We’ve all seen the sloppy wiring job where the wires are loose and the connectors look like they were crimped with a brick or whatever was within arms reach while half of the wire strands are missing.

Using the proper cutting and crimping tools is paramount to guaranteeing a safe and secure connection. Just because you think those side cutters, channel locks or hammer sitting on the bench should do the job doesn’t mean that they will. Each of those hand tools will apply force to the connector differently, and only one type of tool was designed to properly apply force to the connector to keep the wiring snug and secure. “Good enough” isn’t safe enough.


Wiring is not for the impatient or inexperienced. A wiring job done improperly or in a rush can (and will most likely) lead to more than just damaged electronics and inconsistent power, it can actually burn your precious project to the ground. By Holley creating this video, it shows that they are true enthusiasts themselves. They aren’t trying to sell anything in the video and just want to prevent the downfalls of a bad wiring job from plaguing as many of their fellow enthusiasts as possible. Because in the end, we’re all after the same thing — the never-ending search for horsepower.

Be sure to watch the full video above for Kise’s complete rundown on what NOT to do when executing your next wiring task.

Tom Kise shows an example of what a properly wired system should look like, including organized wire leads from the busbar and clean terminal connections.

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About the author

Kyle Kitchen

Born and raised in Southern California, Kyle has been a gearhead ever since seeing his first Mitsubishi Evo VIII in 2003. He is almost entirely self taught mechanically, and as an inexperienced enthusiast always worked on his own vehicles, regardless of the difficulty, just to learn how to do it himself. Prior to becoming a freelance writer for the company, Kyle started his automotive performance career with Power Automedia as a shop technician, where he gleaned intimate knowledge of LS platforms and drag racing builds; then later joining the editorial team as the Staff Writer for EngineLabs And Turnology. Today, Kyle is an experienced EFI calibrator; hot rod builder; and motorsports technician living in the San Jose area. Kyle is a track junkie with lots of seat time. You can usually find him racing his Mitsubishi Evo X in local time attack and road race events.
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