Need Help With EBay Undertail Wireing


One of the Few, the proud -
Donating Member
OK here's the deal, I've been using a mototech undertail for about a year. I bought it when they on there way out (which I didn't know). Unfortunately, the lights quit working, all of them, brake, running and turn signals. I bought an ebay undertail a couple of years ago just in case the one on the bike took a dump.

This is what the undertail directions say "Proceed to do the wiring for the lights (remember all 4 sets of wires must be connected).

Black is ground
Red is brakes
White is running lights
Green is turn signals

Note: You will have 2 wires coming from your turn signals, power and ground. You Only need to connect the power cable and not the ground cable.

However, heres the real deal; the plug that goes to my rear lights has wires for the tail lights, brake lights and a brown wire that comes from the ignition switch. I connected the turn signals, and in contrast to what the directions say, you have to connect the turn signal ground. The turn signals work.

I hooked up the brake lights and the tail lights and they don't work. Probably because I don't know where to hook up the brown wire coming from the ignition. I tried hooking to the tail lights didn't work. I tried hooking to the brake light and blew a fuse. Turns out according to the wiring diagram, that the brake light wire goes to ground.

So at this point, I am pretty much clueless as to where to connect my power/ ignition wire. I hoping you all have some ideas. This can't be this hard..
The brown wire is for constant on running lights... can you post a pic of the wiring that you are working with?
Sean here are three pic of the wiring. Green are turn signals and they work. White and black are running lights, and Black and white are brake lights. The Brown wire with the red extension is the ignition with no where to go. My gut tells me the brown wire should go to the running lights but I've tried this and it doesn't work. Anyhow, any ideas would be greatly appreciated....

Wiring 001 (Small).jpg

Wiring 002 (Small).jpg

Wiring 003 (Small).jpg
The brown wire should be the running lights. Think about it. You turn on key switch, and running lights come on right? Not brake lights or directionals.
+1 on BROWN being for running lights. Stock configuration uses a brown wire for the license plate light, and for the brake/running lamp.

If you don't get it this afternoon, call me. We can set up a time, and I'll come out to you. If I come out to you, be ready for a trip to Radio Shack :laugh:
hey bud i just hooked the same exact undertail up on my busa, you need to conect all of the ground wires together, the green to the turn signals also grounded hook the red to the white and black wire from your harness, and then the brown should hook to the white for the running lights, make sure and ground everything together. if you have any questions or this dosen't make sence give me a call 501-428-3078 brandon, I also had to make so cuts to the stock undertail, and had a few problems with it fitting but finally got it and it looks great and works i will be posting pics in a day or so... hope this helped good luck.
I had the same undertail on mine,good luck seeing the brake light's.The last post was good ,get a test light and see what wire's are what.