I just finished installing some auxiliary LED brake lights on my '06 Vulcan 500. They are a generic setup, so they should work on any motorcycle. It took me two hours to hook everything up, but I'm slow when it comes to electrical work. Someone proficient can probably do this in 30 minutes or so.
The kit I bought was a Rivco S.O.M.A.. (acronym for Stay Off My Ass) L.E.D Lighting Strip for $45 and optional Flashing Brake Light Modulator for $30 that I may get in the future, depending on how well the LEDs work. The modulator is only for the LEDs, so you tail light will work like normal while the LEDs flash, which I like.
Here's what came in the kit. You've got the two brackets that'll go behind the license plate, the two LED strips with red (power) and black (ground) wires, two 3-way connectors to connect the tail and brake lights, fork connector to connecting the ground to the frame (I didn't use this), a tail/brake light module (thing with one red wire coming out one end and a red and an orange wire coming out the other), and a butt connector to connect the power from the LEDs to the tail/brake light module.
In addition to this, I used another butt connector, another 3-way connector, and a piece of wire to connect the ground to the ground wire going to the tail/brake light. Other than tools needed to get the fender off, I just needed a wire stripper/crimper for this job.
Okay, we start by removing the fender to get to the electrical stuff. First you need to remove the seat and look into the battery compartment. You will see five wires on the right side and two wires on the left that need to be disconnected. Those just pull apart at the quick disconnects. The module connected to the fender also needs to removed. It should slide straight up with a little bit of force.
Once you get that all out of the way, you will see two bolts. Remove those with a philips head screwdriver.
After that, you can remove the six bolts holding the fender to the frame. There are three on each side going through the chrome accent pieces. They are all removed with a 10 mm socket. The forward bolt on each side only holds the accent pieces, so remove those first. If you have the rear rack installed, you'll want some tape to protect your paint.
At this point, I brought the fender inside to have a table to work on. Excuse the road grime underneath. First you need to remove the license plate bracket. Two bolts hold it on and can be removed with a 10 mm socket.
Once you remove that, you can see the three wires going into the brake light assembly. On the EN500, the black and yellow wire is ground, the red wire is for the always on tail light, and the blue wire is for the brake light. Double check the wiring diagram for your specific bike.
Here I placed the two brackets behind my license plate for mounting the lights.
I stuck the LEDs onto the brackets and ran the wires out through the holes.
Here I've run the wires to the fender and zip-tied them out of the way.
I connected the two ground wires from the LEDs to a spare bit of wire using a butt connector.
I connected the two power wires from the LEDs to the single red wire of the tail/brake light module.
Using 3-way connectors, I hooked the LED ground wire to the tail/brake light's ground wire (black and yellow). I hooked the orange wire coming off the tail/brake light module to the tail light wire (red). I hooked the red wire coming off the tail/brake light module to the brake light wire (blue). Be sure to strip the wires before connecting them to the harness. They are too thin for the 3-way connectors to slice through the insulation and a connection will not be made if you do not strip the insulation first. I figured this out after putting the bike back together.
I taped up all the connectors and zip-tied all the wire bundles to the fender and out of the way.
I bolted the license plate back onto the fender and double checked the clearance.
I went back outside and bolted the fender and chrome accent pieces to the frame. I left the bolts a little loose at this point.
Back at the battery compartment, reconnect the tail/brake lights and turn signals to the main harness, screw the two bolts back into place, and replace the module onto the fender.
Replace your seat and you are done.
Here is the result.
Tail light only:
Brake lights (terrible picture):
I'll see how well these work. They're not as in-your-face as I would like, so that flashing light module might be in my future.