This modification makes it so that:
When the brake pedal is pushed, the top and middle bulbs bright filaments light up.
When the turn sig is pressed, the top and middle bulbs flash the bright filaments.
When the brake is pushed and the turn sig is on, both bulbs flash the bright filaments.
Note: My TB has a pair of may03 modded tail light boards that were modded so that both dim filaments light up when the parking lights are on. Dual parking lights are not part of this mod, and are not required to have dual brakes/dual turns. (They do look good though).
So, here's how I did it.
I didn't want to cut the factory tail light wiring. So, I bought a M/F connector kit from Ballenger to make a harness.
Note: you don't need the harness if you don't mind cutting your tail light plug. Keep in mind that if you do, you will have live wires that are not connected to anything. If you do it that way, tape those suckers up good.
I made the harness so that 3 out of the 5 slots were used on the male side. This way, the factory tail light connector turn and brake wires were not hanging out in the open. On the female side, a single wire had female pins installed on each end. Those pins were put into the turn and brake cavities. Then, I stripped 3/4" of the insulation, and twisted/soldered a length of red wire to it. (TXBlazer I told you I would use red lol)
For the left harness, the red wire was tied into the yellow wire at the trailer connector harness. For the right harness, the red wire was tied into the DARK GREEN wire in the trailer harness. Keep in mind that there is also a light green wire in the trailer harness and that is not the right one. If you're in doubt, you can easily check it with a DMM. Brakes on = B+; right turn on = flashes B+.
This is a fancy diagram courtesy of my mspaint skills. Yes, it's that easy.
If you want to save $31 in connectors and the cost of a crimping tool, you can do it without the harness. Then the mod will cost under $10.00, BUT YOU WILL BE CUTTING THE FACTORY TAIL LIGHT HARNESSES IF YOU DO IT THIS WAY:
Just keep in mind that those wires that you cut for brakes and turns will still be live.
This was done using halogen bulbs. I'm waiting on some parts to verify that this will work with LEDs. I'm not sure if/how this will work with load resistors for turn signal hyperflash. If you guys running LEDs want to try it before I can, go for it...but your safety is not guaranteed.
UPDATE 5/5/12: This is confirmed to work with LEDs as well. You'll still need to use load resistors for turn signal hyperflash just like you would when you convert to LEDs. Thanks to Short Bus for being the first person to do it with LEDs and confirming that it works!
Also worth mentioning, even with the factory turn signal circuits in the rear not hooked up, the halogens do not have hyperflash when the turn sigs are on.
Fancy tests:
Before
Brake fuse 34 - 4.2A @ 14.43v
L-turn fuse 38 - 5.4A @ 14.41v
R-turn fuse 43 - 5.4A @ 14.41v
After (these will now be your rear brake/turn fuses, in the front fuse block)
TRLR LT fuse 51 -
turn - 4.3A @ 14.61v
brake - 4.2A @ 14.61v
turn + brake - 4.9A @ 14.61
TRLR RT fuse 50 -
turn - 4.2A @ 14.61v
brake - 4.3A @ 14.61v
turn + brake - 4.9A @ 14.61
When it gets dark I'm going to get more pics and I'll also have a vid for this.
Also, shout outs to my man Chris (TXBlazer), without him this would not have been possible!!!
[video=youtube;4zcmmPITB8g]http://www.youtube.com/watch?v=4zcmmPITB8g[/video]