Is there an easy way to find the brake light wires?

dc112675

Joined
Dec 5, 2014
Messages
140
Location
Hobbs, NM
Bike
2004 ST1300A
I have a "tail-blazer" unit which causes the brake light to initially flash when I apply the brakes. To wire it in I need to splice the wire from the pedal/lever. In the wiring schematic the wires are green/yellow and brown/white. I'm guessing the green/yellow is the ground.

In order for the unit to control all 3 brake bulbs (2 in the rear fender and 1 in the top box) I have to wire it in before it splits. Any ideas where a good place would be. Should I be looking for the brown/wire wire? Thanks.
 
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Where did you connect the top box? Why not there?
 
The best place to access the tail and brake light wires is under the pillion seat. Remove the rear seat section and look at the wire bundle that runs along the right frame tube. Follow it back near where the tool kit would mount and the wires will be easy to access.

I never understood why anyone would take the hard way and remove the lower fender and have to reach up in from there. All that does is ensure your connection is right where all the dirt & water hits. Under the rear seat is easy to access, and high and dry once you are done.

When I did mine I mounted a terminal strip there and ran wires to it from each turn signal, the tail light, and the brake light. If I ever wanted to change the aux lighting in the future all I had to do was attach to the proper terminal(s). I used a pair of LED brake/tail lights for a few years which I actually wired up as turn signals and brake lights.
 
nhdiesel said:
The best place to access the tail and brake light wires is under the pillion seat. Remove the rear seat section and look at the wire bundle that runs along the right frame tube. Follow it back near where the tool kit would mount and the wires will be easy to access.

I never understood why anyone would take the hard way and remove the lower fender and have to reach up in from there. All that does is ensure your connection is right where all the dirt & water hits. Under the rear seat is easy to access, and high and dry once you are done.
Click to expand...

+1 on that. When I did some similar wiring I pulled the rear plastic piece below the license plate and then followed the brake wires up to the area under the pillion seat. Once I had them ID'ed it was easy. Oh, and while you are at it, pull the indicator bulbs (under the seat), and use a dab of silicone grease on the rubber gasket. Put them back. The grease ensures you will be able to remove them later, when one burns out. Mine were very difficult to turn to remove the first time.
 
Ok...I am so confused!

I removed the rear fender and determined that there were two sets of wires, each one going to one of the brake bulbs: green/yellow and solid green. Using the "Y" that goes from the brake light area to the top box and a bit meter, I determined the green/yellow was the hot.

For reasons mentioned above, I wanted the unit (1" x1" x 1/2") covered underneath. So I took off the seat, cut into the bundle, and found the two green and yellow wires (I still don't understand why there are 2 sets and not just daisy-chained). Anyway, I cut the two wires, put them into the unit, grounded the unit, and connected the wires going to the brake light. Obviously it didn't work.

So here is where it gets crazy. One green/yellow wire coming from front the front seemingly did nothing. Whether ignition is on our brake is depressed I get nothing. The other one had a constant 14 volts, but when to engage the brakes, it drops to 12 volts and the brake lights turn on!?! What am I doing wrong?
 
Sorry, I'm confused. I thought you said in post 5, it did nothing. Not enuff info here for this Homer. What are you checking it to? Ground? Known Positive?
 
Lol...after reading my post, I'm confused too! I wrote it late at night and kept nodding off...I finally hit send after waking up for the third time with the phone in my hand.

So the ground will show voltage?

I guess I just need to tear into it again and find the other wires. In the process I blew a fuse and ran down the battery. Both issues are fixed but I'm back where I started.
 
Stop mucking around in the dark, and avail yourselves of the multi-colored wiring schematic right here in the ST1300 FAQs.

The schematic can be downloaded and saved to your computer, that way it'll always be there when you need it. The schematic can be viewed by any PDF viewer, which will allow you to zoom in, or zoom out, print the entire schematic (you'll need a large sheet of paper), or print just the area that you're working on.

Come on, some nut spent hours making this drawing just so that questions such as these could be easily answered.

Each of the two tail lamp bulbs has three conductors:
Green/Yellow --- Brake lamps, +12VDC From both brake lamp switches.
Black/Brown --- Tail lamps, +12VDC From Fuse B, of the forward fuse block.
Green --- Chassis ground, 0VDC Direct from chassis ground connection.
 
From the schematic I was wrong. The symptom (power coming from the tail light side, but not from the bike side) acted like a ground would after it was cut. Seeing the schematic (I can't see it on my phone) I would say the wire you cut was running back from a splice to another load (top box? Or unused). Cutting it and wiring in your flasher did nothing because you didn't cut between the power and the brake light.

You said there was another wire of the same color. Most likely that is the feed from the brake light switch and is the one you need to cut.

The reason you got different voltages is that the draw of the light was consuming some power.
 
The way I've always done this type of setup is I leave the bike brake lights alone and allow the top box to do the flashing ... this way you get to different looks and since the top box or aux brakes lights are typically leds these days they can handle a strobe or flashing pattern better without loss of bulb life and you can get that rapid flash which is more attention getting than the slower incandescent bulb flash. I use the 3rd brake light module from www.Motorcyclelarry.com hooked to Hyperlites. This makes the wiring much simpler as you're just taping into the lights you need and not putting something in-between the oem lights which if it fails, no may have nothing. If it fails with my setup, my oem lights should still work.
 
Mellow said:
I use the 3rd brake light module from www.Motorcyclelarry.com hooked to Hyperlites.
Click to expand...

I've been seriously considering Hyperlights on the License plate. My top box has the brake light wired. I went to the web site and got confused on what you did to get your Hyperlights to work since the lights appear to come already capable of flashing.

Wouldn't the 3RD brake flasher module interfere?
Did you get the 19 mode flasher?
What Hyperlight did you get, the universal flasher?
Does clear instruction come with the systems?

Sorry to be slow here but I really don't want to mess up the electrical system.
 
Anna'sDad said:
Stop mucking around in the dark, and avail yourselves of the multi-colored wiring schematic right here in the ST1300 FAQs.

The schematic can be downloaded and saved to your computer, that way it'll always be there when you need it. The schematic can be viewed by any PDF viewer, which will allow you to zoom in, or zoom out, print the entire schematic (you'll need a large sheet of paper), or print just the area that you're working on.

Come on, some nut spent hours making this drawing just so that questions such as these could be easily answered.

Each of the two tail lamp bulbs has three conductors:
Green/Yellow --- Brake lamps, +12VDC From both brake lamp switches.
Black/Brown --- Tail lamps, +12VDC From Fuse B, of the forward fuse block.
Green --- Chassis ground, 0VDC Direct from chassis ground connection.
Click to expand...
Wow, thanks for the link, I have the black and white version and it is nearly unreadable.

Lots of questions, but first, why did Honda run two wires (both green/yellow) to the two brake bulbs? Wouldn't one have sufficed?
 
dc112675 said:
why did Honda run two wires (both green/yellow) to the two brake bulbs? Wouldn't one have sufficed?
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Not sure I understand the question, are you asking why one or the other bulb socket has more than one Green/Yellow conductor (does it)?

Keep in mind that the schematic and the physical wiring harness will differ in terms of how/where conductor splices occur, as well as lengths and routing of conductors. Perhaps it makes sense to think of the schematic has a "road map" of the motorcycle electrical system, rather than an "as built" layout of the wiring harness.

I have a spare wiring harness at home, I'll take a look at the tail lamp bulb sockets with an eye to the number of conductors each has (though I think the tail lamp socket conductors have been modified).
 
Anna'sDad said:
Not sure I understand the question, are you asking why one or the other bulb socket has more than one Green/Yellow conductor (does it)?

Keep in mind that the schematic and the physical wiring harness will differ in terms of how/where conductor splices occur, as well as lengths and routing of conductors. Perhaps it makes sense to think of the schematic has a "road map" of the motorcycle electrical system, rather than an "as built" layout of the wiring harness.

I have a spare wiring harness at home, I'll take a look at the tail lamp bulb sockets with an eye to the number of conductors each has (though I think the tail lamp socket conductors have been modified).
Click to expand...
From the back of the bike there are two sets of wires going to each bulb...Both sets have same colors. I don't understand why there wasn't one wire that split (like a "Y").
 
Reginald said:
I've been seriously considering Hyperlights on the License plate. My top box has the brake light wired. I went to the web site and got confused on what you did to get your Hyperlights to work since the lights appear to come already capable of flashing.

Wouldn't the 3RD brake flasher module interfere?
Did you get the 19 mode flasher?
What Hyperlight did you get, the universal flasher?
Does clear instruction come with the systems?

Sorry to be slow here but I really don't want to mess up the electrical system.
Click to expand...

You can get hyperlites with a steady on / mode but I think you have to cut a wire to disable their flashing. I like the 36 modes of this one.
 
dc112675 said:
I don't understand why there wasn't one wire that split (like a "Y").
Click to expand...

Just a WAG but it might be to keep the left and right taillights independent and minimize a single-point failure for both lights. The left and right headlights are also wired independent of each other to a point.
 
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