How to Wire Running Lights on Tow Mirrors: Step-by-step Guide

In this step-by-step guide, we'll discuss how to wire running lights into your tow mirrors with the Boost Auto Parts Dual Function (Signal & Running Light) Wiring Harness for Aftermarket GM Tow Mirrors Kit.

We'll also cover what additional tools you'll need, as well as a summarized guide for installing reverse and puddle lights.

What You'll Need

The Boost Auto Parts Dual Function (Signal & Running Light) Wiring Harness for Aftermarket GM Tow Mirrors Kit. This harness allows the forward-facing mirror lights in your aftermarket tow mirrors to function as LED running lights and turn signal lights. The type of kit you purchase will depend on whether your mirror lights are dotted or stripped.

Included in the kit are:

Running Light Wires x 2
Running Light Modules x 2
Disconnect Jumpers x 2
T-Tap x 2

Additional tools needed:

Wire Strippers
Wire Cutters
Pliers
Flathead Screwdriver
Phillips Head Screwdriver

Steps for Wiring Running Lights on Tow Mirrors

This step-by-step process details how to install a dual function signal and running light harness into your aftermarket tow mirrors. To ensure you're wiring the running lights correctly into your GM tow mirrors, you must use this kit while following this guide. This harness is compatible with various GM vehicles from 1988-2019.

The procedure must be completed with the mirrors off of the vehicle.

Step 1: Mirror Disassembly

Removing the telescoping arm cover

Each tow mirror has two telescoping arms that connect the mirrors and the mount. The telescoping arms extend the mirror out farther from a vehicle for better visibility of the trailer and road behind it.

Begin by placing the mirror on a workbench or table and extending it out so that the upper arm cover can be removed. Locate the indentation under the upper arm of the mirror; insert a flathead screwdriver, and pop the upper arm cover away from the arm of the mirror.

Once done, perform the same steps on the other side of the mirror to fully remove the upper arm cover.

Removing the glass

Most aftermarket tow mirrors will have an upper and lower pane of glass. To remove the glass from the mirror, adjust the upper glass to the fold-down position. Using both your hands, grasp the lower glass and pull it upwards to remove it from the mirror.

Adjust the upper glass to the fold-up position, place both hands underneath the glass and apply steady pressure to slowly pry up and remove the upper glass. Unplug the terminals for the defrost and signal from the glass (if your tow mirror has them).

Removing the top cap/shroud

You'll note that there are four screws in each corner holding the top cap, also known as the shroud, together. Using a standard Phillips head screwdriver, remove all four screws. Pull up the top cap to remove it from the mirror head and unplug the connector for the reverse light.

Step 2: Module Installation

Installing the LED running lights

Start by unplugging the connector for the front marker light and cutting off the connector, leaving at least two inches of wire. Do not discard this, as you'll need it later.

Taking the running light provided in the kit, disconnect the shorter end of the wire to be run through into the head of the mirror. This will be the side without the inline fuse.

Feed the running light wire through the base of the mount, along the mirror harness, and into the upper arm of the mirror. Continue to run the running light wire along the wiring harness in the telescoping arm into the head of the mirror.

Strip the ends of the turn signal power; this wire can vary in color, so always refer to your manual. In most cases, it is a blue wire. Also, strip the running light wire harness you've just fed through (some may be pre-stripped). Cut the ground wire for the front marker light.

Connecting the module

The module has two input wires and one output wire. On the two output wire sides, you will have two colored inputs (one that matches the color of the wiring harness you've fed through, which will be orange) and one that matches the turn signal power wire (blue). The wire on the single wire side of the module is the output wire (also orange).

Connect the orange running light wire that was run through the mirror to the orange input wire on the two-wired side of the module. Crimp each connection with a plier. Do the same for the turn signals power wire (blue) coming from the mirror harness.

Front marker light connector

Strip both the wires on the front marker light connector you cut at the beginning of step 2. Crimp the power wire on the front marker light connector to the output wire on the single wire side of the module.

Now take the black inline splice (disconnect jumper) from your kit and crimp it to the ground wire on the front marker light connector. Then plug the front marker light connector into the front marker light.

Locate the ground wire (this should be gray) for the reverse light on the mirror. Taking one of the T-taps, place the ground wire onto the metal portion and close it over until you hear a click. Plug in the quick disconnect on the black inline splice (disconnect jumper) to the T-tap tapped to the ground wire for the reverse light.

This kit will have shrink wrap butt connectors which you will need to close. To do this, apply some heat with either a heat gun or a lighter if you do not have one. Do not put the flame directly onto the connectors. Heat shrink all of the butt connectors down to make watertight seals. Tuck the module in the mirror and out of the way of the top cap.

Step 3: Mirror Assembly

MIRROR HEAD ASSEMBLY

Plug the reverse light connector back into the light in the top cap. Pull the wires for the signal on the glass and defrost (if your tow mirrors have this) through the top cap. Reinstall the top cap back onto the mirror head and screw in the four Phillips head mounting screws.

Place the top and bottom mirror back onto the mirror head and press down the glass to reconnect it to the mirror head again. To ensure the mirrors are secured to the mirror head, you should be able to hear a click as you press them down.

Upper arm assembly

Now, place the upper arm cover back into place, making sure that the running light wire is run along the wiring harness and out of the way of the upper arm cover. Push the telescoping arms back together.

Do not pull the additional slack on the running light wire out of the mirror; if you pull any slack out of the mirror arm, you may have issues when telescoping the mirrors.

The last step is to take your tow mirror, install each one back onto your vehicle, and run the long end of the running light wire through the door panel into the vehicle to a suitable running light tap location.

You've completed your running lights installation!

Reverse, Puddle, & Parking Lights

Most GM tow mirrors are already wired to have parking lights, so there is no need to install these. However, if you'd like to install reverse and puddle lights in your aftermarket tow mirrors, you can use the Boost Auto Parts Dual Function (Dome and Reverse) Wiring Harness Kit. This kit includes two light modules similar to the running light modules.

To wire puddle lights into your GM tow mirrors, you first need to ensure the mirrors have the puddle lights built into the lower part or underside of the mirrors.

The installation is relatively easy to complete. The two modules in the kit each have two orange input wires and one blue output wire.

Remove the parking light fuse panel that sits on the right and left sides of the dashboard. Unwrap the harness tape around the loom of wires to the left of the fuse panel to locate the reverse and puddle light wires. Splice the ends wire with a T-tap. These will be your input wires for the modules' two outputs.

Now with the two output wires, this is the wire that controls the lights towards the rear; you're going to strip the ends, twist both ends together, and place them into the module's one-sided output. Crimp and shrink down all three butt connectors.

To review, you'll have the single output and the two inputs. One of the wires from the two input side will run to the underhood fuse panel to the trailer backup fuse, and the other will be tapped into the puddle light output.

Conclusion

Just like that, you now have running lights wired into your tow mirrors. This guide is compatible with the Boost Auto Parts Dual Function (Signal & Running Light) Wiring Harness for Aftermarket GM Tow Mirrors Kit, so be sure to use this kit when following this guide.

Moreover, if you want to install reverse and puddle lights, be sure to use the Boost Auto Parts Dual Function (Dome and Reverse) Wiring Harness Kit.