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· Premium Member
15,676 Posts
Discussion Starter · #1 ·
This mod allows you to add additional back-up lights to brighten up the area behind you when backing up. The idea is for the lights to only come on when dark, since there is no need for extra light during day light. This mod enables power to the auxiliary lights only when the vehicle is in reverse and when the running lights are on, it takes both to send power. The lights I used are not water proof since I don’t tow a boat; I bought a cheap pair of very small halogen fog lights so that they wouldn’t be very noticeable, but if the rear of you truck is going to be in water you may want to go a different route. My explanation of this mod can be redesigned or changed up in many ways, but it worked well for me, if you have improvements to it let me know.

What’s needed:
Fog lights (or any 12v light source)
(4) Different color strands of 14ga wire about 6ft or so the size may be over kill but its what I had laying around
Black wire conduit to cover and run wire
Tie straps
Electric tape
Soldering iron/solder
Heat shrink
Ohm meter
Wire *****
T-15 star bit
Clamp-on wire connectors
Female crimp terminal
Philips screw driver
Flash light (even better shop work light)
Sheet metal screws and nut driver

Acquired from radio shack:
30 amp auto relay……part# 275-226
Auto inline fuse holder…….part # 270-1234
Project enclosure 3”x2”x1”………part # 270-1801
30 amp fuse

I drove my truck up on ramps so it would be easier to crawl under while wiring.
First I used the T-15 star bit to take the driver side tail light assembly off to identify the wire colors of the back up lights and running lights. I did this by getting someone else to turn the lights on and off and putting it in reverse while I tested the connectors. I determined that the running light wire was BROWN and the back up light wire color was BLACK W/ PINK TRACER. After the wire colors are determined the taillight can be reinstalled.

Under the bumper near the same tail light follow the group of wires bundled up from the tail light, here you can tie into the running and back-up wires with the clamp on connectors. Leave enough wire to make the required connections 3ft should be enough.

Next I decided to mount the fog lights and run the wires to them. Under the tow hitch on the ends there are ½” hole on each end. This is where I chose to mount my lights, but they could be mounted anywhere even on the bumper.

Run wires from the fog lights to under the tail light in the same vicinity that the clamp on connections are made. Make sure to insert the 30 amp inline auto fuse in the power wire of the lights and make it easily accessible incase a fuse is blown. Wrap the wires up in the black conduit and tape up, then zip tie the conduit to the top of the tow hitch out of site.

Drill a ½” hole in the bottom of the project box; this is for the wires to come in to the box. Also while your modding the box shave down the inner most raised screw holes, this allows room for relay to fit snuggly. I did this by just taking a drill bit larger than the diameter of the screw holes and drilling them down.

Connect your ground wires from your lights and another loose ground with a female crimp terminal on it by screwing it somewhere under the truck or piggy backing another ground, I used a sheet metal screw, (the loose ground wire is attached to the relay) Mount the project box to the thin piece of sheet metal that is below the taillight, I used sheet metal screws, first I put one screw in the bottom of the box, the second screw will go in later. Run the four wires (fog light, ground, running lights, back-up) through the hole in the project box and connect to the relay as follows:
Terminal #87 – (12v in) running lights
Terminal #86 – (on/off switch) back-up lights
Terminal #85 – (ground) ground
Terminal #30 – (12v out) fog lights

The relay has a tab at the top of it with a screw hole, I put the second screw through that hole and into the project box, and this holds the relay in place and secures the box to the truck.

Tape up any loose wires and wrap all in wire conduit to minimize any water from entering connections. Ensure all wires and conduit is zip tied out of the way of any moving parts. Screw the cover on the project box.

Total time on mod was approx 2 hrs, cost was about $40, that’s $30 for the fog lights $6 for the relay, $2 for inline fuse holder and fuse, $2 for project box, those prices aren’t exact but close enough to get the idea. This mod could cost as much or as little as you want depending on the lights used. This was done on an 04 excursion but the concept can be used on any vehicle. After I was done I wanted to see what the difference in lighting was, I noticed a gain from visibility at roughly 20ft to visibility of roughly 40ft. I angled mine outward to also give me better visibility on the sides for mirror view. These pics don’t really do it justice but you can get an idea of the gains.

A higher quality monitor will probably allow to see the last pics better I noticed my work monitor isnt near as bright as my home monitor.

· International Threat
13,235 Posts
Or if you're a cheap SOB like me you can do this...

I ripped some foglights (and mounting bracket) off an early 90's Grand Am (work great) and just wired them up to the reverse lights. All water tight and works great. The foglights are mounted sideways so they're above the hitch so anytime off road I wouldn't RIP them off...

Hahha, figured this would help lol.

· Premium Member
14,523 Posts
Cool! Thanks for the ideas guys and GREAT write up Stumpy! :)
I've been looking for something to do while I'm saving up for my next "big" mod and something like this would be great.
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