If you have ever wanted to upgrade the headlights on an early 2000s Dodge Ram, you already know these trucks are not as simple as pop the bulb out and drop a new one in. In this guide we walk through a complete Dodge Ram HID lights install on a 2004 Dodge Ram 1500 using a GTR Lighting dual beam HID conversion kit, a relay harness, and a 907 resistor kit. We tested this setup, installed it start to finish, and documented every step so you feel confident doing it yourself. The tricky part with these Dodge and Chrysler trucks is the early CANbus system, so we will also show you how to trick that computer using resistors and a capacitor.
What This Kit Is and Why We Chose It
We are really excited to show off this kit by GTR Lighting because it has one of the best HID relay harnesses on the market for any HID conversion kit. A dual beam HID bulb (also called a bi-xenon bulb) uses a single bulb that moves or switches to provide both low beam and high beam functions. That means one bulb, one ballast, and a clean install. The 2004 Dodge Ram in this install uses the 907 headlight bulb, so the entire kit is built around that bulb size and its factory connector.
If you are shopping for parts and want to compare options, take a look at the 9007 XTR HID Conversion Kit along with the full lineup of HID resistors and relay harnesses we carry. You can also browse the complete Dodge Ram lighting catalog if you want to see everything that fits your truck.
Removing the Factory Headlights
The first step in any Dodge Ram HID lights install is getting the factory headlights out of the way. To do that you are going to need a 10mm socket (a ratchet works fine, we just used power tools for the sake of the video), a basic Phillips screwdriver, and a longer extension. There are two 10mm bolts along the top of the headlight assembly that come out quickly. Next there is a Phillips clip that sometimes just spins in place. If it keeps spinning, reach behind it and pinch the tabs together and it will come right out.
The only tricky part about removing these headlights is one hidden bolt. You are going to want a longer extension, and we prefer a quarter inch drive for getting between the bumper and the headlight, because there is one bolt located underneath the headlight right below the turn signal. Just push down on the plastic of the bumper and sneak back there to reach it. Be careful, because if that bolt falls it will hit the ground. Once that bolt is out, put your hand underneath the headlight to prevent scratching the bumper and ease it out. If it gets hung up, shift it side to side a little. Then unplug the two connections in the rear, one for the turn signal and one for the headlight bulb.
Installing the Dual Beam HID Bulb
These dual beam bulbs come with a removable collar, and the install order matters. Take that collar off and set the bulb to the side. We already cleaned the bulb with alcohol so there are no oils on the glass. Install the collar into the headlight assembly first, rotating it until it seats into place. It should go in evenly all the way around, so if it is crooked at all, keep spinning it until it sits flat.
Once the collar is in, grab your factory locking ring and install it. Then to install the bulb itself, just insert it and turn it. You will feel it engage, and at that point you are good to go. This part of the process is simple once you understand that the collar goes in before the bulb and the locking ring.
Installing the Relay Harness
There are three parts to installing a relay harness. The first part is connecting it to the battery. The second part is connecting the harness to your factory vehicle headlight harness. The third part is connecting it to the HID ballast and then to the bulb. What we usually do first is lay the harness out over the front of the vehicle and grab the parts we need as we go.
If you are not sure whether a relay harness is right for your situation, we broke it down in this article: Do you need a relay harness for your install?
Part 1: Connecting to the Battery
To connect to the battery on this Dodge Ram we need a 10mm socket. We can connect right to the positive battery terminal without removing it. Loosen the 10mm nut, slip the ring terminal on, and tighten it back down. Because you never fully remove the terminal, you will not lose any radio settings. All of this can be done with hand tools, it just takes a little longer.
Part 2: Connecting to the Factory Headlight Harness
Next we run the headlight harness and the ballast harness down to the headlight area. On this truck it is really easy, you can go right in front of the fuse box and get all those connections down there with little hassle. Some vehicles are not as simple, but this Ram makes it convenient. Down in the headlight area you have the factory connection and the relay harness connection, and all you have to do is connect those two together. There is a lot of room back there, so you can stuff the wiring in and zip tie it up nice and neat afterward.
You always have to find a place to mount the relay box itself, and this is important: always mount it upright with the tab facing up. If you mount it downward, even though it is a fairly watertight connection, water can still get in there and corrode the relay and cause it to fail. On this vehicle it is simple to zip tie it to the existing factory harness right next to the fuse box, keeping it dry and easy to service later.
Part 3: Connecting to the Ballast and Bulb
We are using the GTR Lighting 55 watt ballast for this install. There are two ways to mount it. If you have the room (and this truck certainly does), you could use a self-drilling screw into the sheet metal, or you can zip tie it. For the sake of the video we zip tied it up out of the way, but it is up to you. Either way it stays protected from the elements.
The connections here go to the bulb as well as the two pin high beam connector. Connect the ballast lead from the relay harness to the ballast and make sure you hear that click. If it does not click, it is not seated all the way. Lastly, ground the harness. On this truck there are conveniently two 10mm fasteners down low that you can remove and connect the ground ring terminal to, so you do not need to drill any new holes.
If you do have a different vehicle and you have to drill, it is not a big deal. Find something that is relatively thin sheet metal, use a self-drilling screw, and most importantly paint it so it does not rust. Rust can corrode the connection and give you a bad ground, and a bad ground is the last thing you want.
Dealing With the Dodge CANbus System
Here is where these Dodge Ram trucks get interesting. In the early 2000s Dodge and Chrysler started experimenting with a new technology for controlling their lighting systems called the CANbus system. We are not going to go into deep detail here, there is plenty of information online, but the short version is that the CANbus computer monitors the electrical properties of your bulbs. If it does not see what it expects, you get error codes, flashing lights, and sometimes the lights just go out completely in the middle of nowhere.
The way we trick it is by mimicking the properties of a halogen incandescent bulb. We do that with resistors, because what is inside the resistor behaves like an incandescent filament. When we install the resistors in line with the relay harness, the vehicle thinks it still has the correct factory headlight bulb installed.
Installing the 2200 Microfarad Capacitor
The second step to tricking the Dodge computer is installing a 2200 microfarad capacitor. The capacitor has a marked ground side (indicated by arrows on the shorter leg) and a positive side (the taller leg). We install this on the low beam circuit. When you look at the headlight bulb, ground is in the middle, low beam positive is on the right, and high beam positive is on the left. We install the capacitor on the low beam wiring, and the easiest spot is right on the 907 resistor harness.
To wire it up, we strip the wires to expose the copper, wrap the legs of the capacitor around the exposed copper, solder the connections, trim the extra wiring, and then tape each connection individually to insulate it. Once it is insulated with electrical tape, the arrow side (short leg) goes to the black ground wire in the middle, and the side without arrows (long leg) goes to the positive low beam wire, which is red here. We do not need anything for the high beam on this particular vehicle.
Plugging In the 907 Resistor Harness
This is a 907 resistor harness designed to be plug and play from GTR Lighting. It is compatible with GTR Lighting HID kits and makes adding resistors really easy. To install it, unplug the factory headlight plug, connect it to your resistor harness, and then connect the other side to your relay harness.
Keep in mind you only need the resistor harness and the capacitor if you are working on a Dodge Ram with this CANbus system. Most of the time on other vehicles, all you need is the HID conversion kit with a relay harness.
Mounting the Resistors to Metal
These resistors will get warm, so you want to install them to a metal surface to dissipate that heat. On these trucks that is really simple, there is plenty of room right on the frame. Grab your drill and a self-drilling Phillips screw and anchor them to bare metal. It does not matter exactly where they go, they just need to be secured to metal. One screw, two screws, and that is it.
Reinstalling the Headlights
Reinstalling the headlights is the exact opposite of removal. You have a total of three 10mm bolts, that little Phillips clip, and that is really all there is to it. Connect your turn signal, seat the headlight back into place, and thread the fasteners back in. Compared to the rest of the install, the passenger side is extremely easy, since after the bulb is installed and connected to the relay harness, you just plug the resistor harness into the factory plug and drill the resistors to metal. Tuck away the extra plug, zip tie it out of the way, and your resistors are good to go.
Other HID System Options Worth Comparing
The GTR Lighting relay harness is our favorite for a reason, but it is always smart to understand your options before you commit. If you want to compare against other engineered kits, look at the Morimoto HID systems as well as the GTR Lighting 9007/9004 HID system. Comparing systems helps you match the right ballast, harness, and bulb to your specific truck and CANbus needs.
Frequently Asked Questions
What headlight bulb does the 2004 Dodge Ram use?
The 2004 Dodge Ram in this install uses the 907 headlight bulb, which the dual beam HID kit is built around.
Why does this Dodge Ram need a resistor harness and capacitor?
Dodge and Chrysler used an early CANbus system that monitors bulb electrical properties, so a resistor harness and a 2200 microfarad capacitor on the low beam circuit are needed to mimic a halogen bulb and prevent error codes or light failure.
What tools are needed to remove the headlights on this truck?
You need a 10mm socket, a basic flathead screwdriver, and a longer quarter inch extension to reach a hidden bolt located below the turn signal between the bumper and headlight.
How should the relay harness box be mounted?
The relay harness box should always be mounted upright with the tab facing up, since mounting it downward can allow water to enter and corrode the relay even though the connection is fairly watertight.
How many steps are involved in installing the relay harness?
There are three parts: connecting the harness to the battery, connecting it to the factory vehicle headlight harness, and connecting it to the HID ballast and bulb.
Meet the Experts Behind Headlight Revolution
Chris Nelson – Founder
Before founding Headlight Revolution in 2011, Chris worked as an automotive install technician specializing in lighting, sound systems, and engine performance parts. He has personally tested thousands of lighting products and works directly with lighting engineers to evaluate the technical performance behind every recommendation.
Josh Beberg – Content Production Manager
Josh leads hands-on testing and content production at Headlight Revolution. From beam pattern comparisons to real-world installations, he works directly with lighting engineers to ensure every review is grounded in measured results, not marketing specs.
