Off
Backup
Brakes
Rear Fog (running lights also turned on; necessary to turn on the rear fog)
The idea behind the mod is really very simple. My bumper light has both a red lamp (for brake and rear fog) and a white lamp (for backup). I used a clear (2004 backup) lens assembly and hooked it up to the backup lights in the taillights. This makes it operate as a third backup light. Then I added a red lamp to the enclosure and connected it to the factory rear fog harness, and I applied mini-roll's mod that makes the factory harness operate as both a rear fog and extra brake light. The end result is a single enclosure that lights up both red and white, and performs all the functions: brakes, backup, and rear fog.
Here is what I did. Hardcore DIYers can assemble all the components separately, but I used mini-rolls' kits from MyMiniParts to make the project easier.
My 2006 MCC came without the rear fog option, so it had only the rubber plug in the bumper, but it was prewired for a rear fog light. I started with mini-rolls' 2005 Backup Light Kit: http://myminiparts.com/proddetail.php?prod=MMBUL.
This kit includes a clear lens assembly for the bumper, and a jumper wire. The instructions describe how to connect the jumper to make the factory rear fog harness function as either an additional backup or brake light. I installed the jumper for a brake light.
I also purchased mini-rolls' Brake/Backup Light Harness Kit: http://myminiparts.com/proddetail.php?prod=BBLH
This is simply a two-wire harness with connector, to run from a taillight to the fog light fixture. I quick-spliced the wires to the backup light in the taillight. The connector will be plugged into the bulb of the clear lens assembly. After installing both kits, the result is that there two wire harnesses going to the rear fog location. One harness (the new added harness) is to connect to a white lamp (backup), and the other harness (the factory rear fog harness) is to connect to a red lamp (brake and rear fog).
Next is to add a red lamp to the clear lens enclosure. I discovered a flat LED lamp that is compatible with a 1156 bulb (the type used in the rear fog):
http://www.superbrightleds.com/other_bulbs.htm. Scroll down to the item "12VDC 1156/T10 PCB LED Lamp". I purchased the 1156 Red lamp for $10. The lamp is a 36-LED array that looks white but lights up red. Here is the light assembly and LED lamp:
I cut a square hole of about 38 mm into the top (the flat side) of the enclosure.
I made the hole just large enough that all of the LEDs fit through, but the edges of the circuit board overhang the sides of the hole.
I don't have pictures for the next few steps. The LED lamp needs to be connected to the factory rear fog harness, but it should be unpluggable for service (such as removing the rear bumper). On the factory rear fog harness, use quick-splice connectors to get an extra set of wires coming off of it, for connecting to the LED. On the LED lamp, cut off the 1156 bulb plug, and extend the wires so you have more length to work with. Then attach connectors to the wires (I used tongue shaped "quick disconnect" connectors) that allow you to plug and unplug the LED from the factory harness.
The final step is to glue the LED circuit board to the hole in the light assembly, and protect its back with something such as vinyl tape. My final result looks a bit messy, but the back of the LED lamp is sealed and protected.
This setup produces good light from the red LED lamp, though not anywhere nearly as bright as the OEM rear fog. LED light is very directional, and its light should be directly aimed at the viewer for greatest intensity. Although this lamp has 36 LED elements, they are all pointing down and all of its light coming out is reflected, not direct. With the brake lights activated and viewed from straight back, it is similar brightness to the 3rd brake light over the tailgate (which is also LED).
I think I have taken the project as far as I want to, but there are some possibilities for a brighter red light. However, the goal should not be to match the brightness of the OEM rear fog, which would be glaringly bright as an additional brake light. Mounting the LED lamp at the bottom surface of the light enclosure might make it appear brighter because some of the light might possibly be directly viewed. I mounted mine on top because it is a flat surface (a little easier to work with), and there seemed to be less potential for any clearance problems when sliding the light assembly in and out of the bumper. It may be possible to mount LED lamps on both top and bottom for a whopping total of 72 LED elements, which should produce a very bright red light. However, adding the LED lamps effectively makes the light assembly thicker in size. With LED lamps mounted on both top and bottom, I'm not sure whether it would would have clearance to slide in and out of the hole in the bumper (but it should be easy to trim the inner flange of the hole that is visible in the photo).
This was one of my earliest mods on my MCC, and at the time I had minimal experience working on the car. The project simply started out as an idea with uncertain outcome, and I'm thrilled (and I must admit a bit surprised) that it actually worked so well.
Credit to RKW of NorthAmericanMotoring.com