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I am admittedly a novice when it comes to electrical stuff, but I am willing to try and that's why I need your help.

I purchased an electrical modulator with a three wire hook up. Easy right? Well not for me. The three wires that come with the unit are:

1. red - connected to an inline fuse that goes to the 12V
2. black - ground
3. white - connects to the bulb

When I removed the brake light cover there were three wires connected to the bulb - brown, gray with yellow stripe and gray with black stripe.

I tried all possible combinations and cannot get this to work. Assuming the modulator is not broken, what could I have done wrong?

I have scanned the instruction sheet into jpeg format. Not sure how to attach it to this post.

Thanks for your help!

the three wires going to the bulb:

one is a ground, one is for the "brake" (bright) light when the brakes are applied, the other is a "tail" light which is always on.

not sure on the colors but i would guess (you should check this before blowing your fuses) that brown is the ground.

I would guess the 12v wire with the fuse should be connected directly to the battery, ground to any ground, and the other should be spliced to the "brake" light wire.

uneducated guesses, so take this advice for what is cost you!

You were right. The brown wire is the ground and the Gray wire with the yellow stripe is the "brake" wire. Here's another silly question - How to I connect the 12V wire with the fuse to the battery? I tried connecting it to the #1 fuse in the fuse block and the thing didn't work. I just pulled the fuse out, put the wire into the slot and replaced the fuse. Is there a more elegant way to make this attachment to the battery? Should I connect this wire to the third wire on the light itself (the one that is always on)?

H8terboi wrote:...Should I connect this wire to the third wire on the light itself (the one that is always on)?

That is what I would do...its a 12V power source that is only on when the bike is turned on, and its fused.

that solution (using the tail light wire) may work. I would take it directly to the battery itself. This means you will need to take off the tank. I have no idea how much current the modulator draws, and may possibly cuase a wiring harness meltdown (see other recent threads) if your modulator goes all wonky.

pulling the tank is not hard, it often causes first-timers headaches though.(see many threads regarding fuel disconnects, clamps, vent tubes)

I have installed a number of taillight modulators/flashers on various motorcycles (one I used, has some FAQ's, etc). Even though yours may not be the same as this, I am pretty sure they would all install the same way. Just make sure you know which wire on the unit does what.

The hot line does *not* go to the battery. directly. The unit needs to be installed such that it "interrupts" the incoming line to the brake light(s). Its a solid state relay and acts as an "extra" switch to automatically turn on/off the lamp for you one once the power associated with powering the lamp is applied to the device instead.

I will try a diagram....



|---------------------------------------------------------|| Ground
Brake OO= -----------------------x x---------><o><------o +12v
White | | Red ^ ^
\ / |____ Bike Brake SW(s)
|__|
| |
| M | <- Modulator/Flasher
-------
|______________________|| Ground
Black


Its an exercise for the student to figure where the spaces were removed from the above diagram. Sorry, don't see a way around this software....

I will post a small JPG file of the diagram to this thread.

Its important that the Red and White wires are attached to the proper side of the break you put in the wire. Once the power flows into the Red wire from stepping on the brakes, the White will intermitantly turn on/off the lamp per specs. The device needs the ground for the electronics to function.

Note that the break in the wire where the modulator goes is *after* the two (front & rear) brake light switches on the bike. Each of those switches independently powers the wiring circuit to the rear brake light.

I am not sure why they put a fuse on the red input wire. Maybe to keep people from trying to modulate a gazillion brake lights. The one I used could handle 15 amps (~100 watts), which is a lot of brake lights, and a whole lot of LEDs.

BTW - you may try disassembling the plug at the lamp socket containing the "brake" line so that you won't have to cut the wire. Use the proper male & female spade plugs to put the modulator into the circut that way. You can also use the lamp's ground wire in a similar manner.

It may be just me, but I would suggest that you use the modulator to flash some auxillary brake lights (LED banks or whatever), and that you leave the factory circuit and taillight alone. Provides a level of redundancy. And if the modulator fails, you will still have brake lights.

This approach also allows the use of a tap on the brake wire instead of having to cut it. ALSO - if you do put in breaks, use of solder is recommended over just crimping stuff, and try and use heat shrink tubing over those splices.

Hope this helps, and doesn't confuse.

Yes, I am one of those geeky engineers. PM me if you need additional clarification(s).

Picture?




Guess who?

don't listen to me. Listen to him! i wasn't understanding exactly what that device was

i thought it was more of a an accessory flashing brake light.

sorry for any wasted time. i'll just shut up now

So the first one didn't work and I got the manufacturer to send me another one. That didn't work either so I called them today. I was connecting it the correct way... the way that is diagramed above. Unfortunately I think the current to the light was too high for the modulator and it fried. As least that is what their tech guy told me. The are making me one that can handle the higher current and sending it to me next week. As far as attaching LED's and not modulating the brake light... that's too high end for me. I can't even get this simple three wire installation to work