Thread: Rewiring taillights to make more sense 04+

Yeah it sounds pretty simple, but I'd like to see it done as well.

As all of you know by now this is what the 04+ taillights look like from the factory. Just a third brake light and the lower half of each taillight as a brake light/turn signal.


This is what this modification will make your taillights look like when completed. Still the third brake light only now both the top and bottom of the taillight are brake lights. Also, the top half of the taillights is now the turn signal function as well. Below are the steps you need to do as well as a list of materials needed.
1: short piece of stranded wire (16 gauge minimum) about 10-12' (can't remember exactly how much I used as it's been a while)
2: new or used taillight sockets with 3 wires instead of the factory 2 for the upper sockets
3: pigtail splices
4: butt splices
5: razor blade or other sharp knife
6: new bulbs (not really needed, but since you'll have the lights off you may as well)
7: about 30-40 minutes of your time and as always a bit of patience

OK, so now that that's out of the way, here's how you go about doing this. First step is removing the taillights and putting them on your work surface. Take the sockets out. Now take the new socket and compare it to the hole. You'll see it won't go in. You'll see the tab that needs to be modified so it will go in. Line it up, Mark it and cut off the offending area.



Your cut should resemble this. Now cut the yellow wire leading to the bottom socket with enough to work with on either side. Splice the yellow supply wire to the top socket yellow wire. Splice all the other wires accordingly. I cut one wire at a time on the old socket and spliced them one at a time so as not to mess up which wire did what.



You're finished splices should look like this. You'll notice the yellow wire leading to the top socket had to be extended a small bit. Now run your wire into the car through the rubber grommet for the taillight wiring. I don't think I had to cut a hole in it to do so, but you might have to to gain the necessary room for the new wire. Just make as small a hole as possible so you don't have to seal it later. Run the wire as neatly as possible so you don't see it when you're in your trunk unless you're looking for it. Now using a pigtail connector splice into the white wire in the harness that goes up to your trunk lid.

This harness. Make sure to splice into it before the plug so if need be trunk lid can be unplugged and removed properly/easily.

This white wire. Now repeat for the other side, except splice into the new wire for that side so you don't have to disturb the factory wire more than you need to. Hopefully the pictures work.

Cool mod.

You should at least tape those crimps. Ideally, re-do them with shrink-tubing.

I notched my tail housings to make the sockets fit (flat file, 1/4" shaved, 30 seconds each, no problem!), but otherwise had the same idea. Going to the next level though, to get fully independent indicators, will involve a 2-to-3 converter like you find in cars pulled by RVs; the combination signal (yellow wire #43 & dk. green wire #48 on the BCM C2 connector [on 04 at least; later cars might differ]) would splice into the converter's combination input, and the dedicated indicator output will pick back up with the yellow & green wires, and the dedicated brake feed can either go into the white brake feed (#30 on the same C2) or run new lines to the back, though I'd go with wiring through the 3rd brake, as that'll keep the system from being confused when the 4-ways are on! Would love to have amber turn signals (like my '89 GP), but even the bespoke tail light shops can't be ersed! Modify Spyder LEDs? One thing at a time...

resurrecting zombie thread, but if anyone has done this and has pics that work, I'd be very appreciative.

How much of a difference does this make in light output for the brake light and turn signal?

I don't think it makes any difference in light output, I just think it makes more sense for the lights to be wired as brake on the bottom, and turn/tail/brake on the top.