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How To: Install 7" Round LED Headlight Set & Heavy-Duty Headlight Wiring Harness

Project Overview

In this video, you'll learn how to install a seven inch round LED Headlight and Heavy-duty headlight wiring harness. LED headlights improve safety, visibility and produce a bright white light perfect for driving at night.

Project Difficulty
Estimated Project Time
2 hours
Required Tools
  • Socket Set
  • Wrench Set
  • Test Light
  • Sandpaper

Video Transcription

Hi, I'm Kevin Tetz, working with LMC Truck to bring you some technical information in videos that are designed to make your truck project go even easier.

In this video we're going to address the issue of yellow and dim headlights in a classic vehicle. In our case it's a 1971 Chevy c10 pickup. Now there's a lot of things that can contribute to these dim yellow headlights. One of them being the crazy path the current has to follow from your battery to the headlights themselves. Another one is just that we're dealing with old technology in these sealed beam headlights and part of the solution maybe just a headlight bulb upgrade in the first place.

LMC Truck has several different bulb upgrade options including these halogen conversion bulbs for both two and four bulb configurations. They feature a clear no diffused lens a much brighter reflector and halogen bulbs themselves which offer a brighter light. They also have the pigtail harness that converts the newer style bulbs to your old style harness.

The next evolution in headlight technology is LED and it's no accident that most modern vehicles are equipped with LED headlights now. LED has less current draw it's a much more natural and bright light and the bulb life is so much longer. These lights feature a polycarbonate lens for extra strength and the best thing is that they are plug and play and will work with your original harness.

Now one of the upgrades were going to be doing today is installing this heavy duty headlight harness which draws power directly from the battery, has relays to handle that power it has all preterminated ends so you don't have to cut or solder and everything's very clearly labeled it plugs right into your existing harness and just takes a little while to install. Now anytime you’re dealing with the vehicle this old let’s face it stuff just wears out and the LMC Truck catalog and website is full of the different things and replacement items that you're going to need in a restoration. Things like a voltage regulator, the headlight switch or the dimmer switch itself which was actually the problem on our 71 here when the headlights wouldn't work. A few dollars later now we're up and running. We've got lights again. Now if your harness has been hacked up over time like a lot of these old trucks have LMC truck also has this complete harness that goes from the bulk head out to the alternator and to both headlight loads it's a complete drop in original equipment replacement harness that looks factory correct. And you may not need everything we've shown you here for your headlight upgrade but it's nice to know that either in the catalogs or at you can pick up everything that you need to completely rebuild and restore your truck.

For a difficulty scale this project is truly easy its plug and play so I'm going to give it a one and a half out of 5. Now you will need some tools a standard socket set and some wrenches maybe even a test light to verify some circuits but it's truly plug and play and you can get this done in a couple of hours of your time. You do have to get some stuff out of the way first though. First things first, we get our negative terminal disconnected out of the way. Sophisticated battery hold-down goes away. We can get our battery cell out of the way, boy it looks like it for a lawn mower. We're going to get a battery box out of the way. Last bolt... This truck was converted to look like a 1969 and 1970 model by the previous owner but checking the VIN tells us it's definitely a 71.We're going to ask our battery box nicely to leave the truck. Now we pull the evaporative canister out of the way just so we can have access to this right here which is the headlight plug. The radiator hold down brackets come out just so we can have access to a nice route Come on... Please...There we go...

This headlight harness is ridiculously simple and brilliant in how it works. It draws power directly from the battery and your switch on the dash is now just an on off drawing power from the battery instead of going from the battery to the fuse panel to the switch to the dimmer switch then out to the lights. It really simplifies and circuit and gives you that 12 volt power right to the lights.

We’re going to follow our original harness routing, utilize the radiator support. Make sure you secure the heavy-duty harness safely with cable ties or clamps to make sure it doesn't get close to hot or moving parts. Here is our headlight plug which we could find conveniently right down there by the headlight. Now this is critical you have to ground this system properly our ground locations right here, right in the factory location. Okay, before we do anything else we've got to do something about the ecosystem that’s been building here. This dirt dauber that's got to go away. And the wasp nest in here, sorry guys you’re moving out too. But here, look at this, this is about four inches of just packed stuff. If that gets moist it is going to corrode and rust that fender. So, this has got to go.

I'm going to unplug the passenger side headlight and plug our heavy duty harness into that plug. Now the heavy duty harness here this plug goes back into the passenger side headlight that’s what makes our switch work and gives us direct power to the headlights. Now just like the other side we have to establish a good ground and again just like the other side we've got a factory ground location right here at the battery strap went to, so we can use this but we've got to clean it up first. A little bit of sand paper gets the scaly rust off of there. That gives us bare metal and a perfect ground. All we're doing is completing the circuit.

Alright now you do have two relays that you have to mount. These already have a loop in the top so you don’t have to drill and you could use some cable ties and cable tie them to an existing wire or a bracket. I like the way they look right here to me it looks a little more professional. So I'm going to drill a couple holes and mount them up here but you don't have to, you do have options for this setup. We can put back our evap canister. Nice and snug. The world’s longest bolts are now tight. Interestingly enough this was held in place with a bungee cord and there's actually a battery hold down so we're just going to use what's already there.

Now that is mounted tight and looks a whole lot better too. Alright so our new power leads go, like I say, to the battery. And this looks like a mess. But what it really is an opportunity to clean everything up and make sure we get a really solid connection. So we're just going to disassemble this and take advantage of the way this all goes together. Clean it all up. We will be connected. Use a wire brush to clean some of the nasty oxidation off of those wires last but not least, the terminal from the relay, good and snug there...I'm going to tighten up this guy. Reinstall the battery ground strap. I'm going to clean the ground strap up first. Much better okay, now we can hook up the negative lead on the battery. Let’s give it a shot.

Now you can see this is brighter than it was before and it's going to be way more consistent because it’s not susceptible to pulsation from the alternator or faulty grounds somewhere else in the system. But it's still old technology sealed beam headlights and we can do a lot better. It’s amazing that didn't break. The old technology is tough. Alright, let's see what we have. Well, the original lighting is brighter is going to be way more consistent since it's drawing power directly from the battery and not all the way up in the cab from the switch. And the LED lighting well let's face it, looks great, it’s cool, it draws less current and is just plain brighter which makes your truck safer. It's important that you can see but it's important that people can see you as well. The one thing I really want to drive home is to make sure your ground connections are solid and well connected because 90% of all electrical problems come from a faulty ground.

We hope this video has helped you with some techniques on how to take that yellow dingy lighting away from your old antique truck and bring it back into the21st century. Don't forget to go through the catalog and go to for other lighting ideas and ways to make your truck project even better. For now I'm Kevin Tetz, see you next time.