Rear Light replacement help

Hey There,
Trying to replace my rear tail light. I can't figure out what to do with some extra wires. A red, black and white wire enter the actual tail light and attach to the plug in at the harness. Now I have a blue and yellow wire that I can't figure out what to do with, and the tail light is not working at all. Any suggestions?

This might help: http://keysdog.com/YamahaWR/WR250RX%20Wiring%20Diagram.jpg

Thanks for the diagram link Now that I am home from work I can provide more information. I bought a 2001 (?) R1 tail light as a replacement since they are the same and way cheaper.

Things I have checked:

1. Fuses are all good
2. Checked power at female connector from harness-~13v
3. plugged in new light checked that I was getting power to the same wires- 13v
4. The two extra wires are for the license plate light, which I don't have.
5. Headlight works
6. Signals work

7. What do I do with the licence plate wires? Do I connect them together and cut or just wrap and tape away?

So even though I am getting power the light isn't coming on at all (this is with engine running), this sort of leads me to think maybe a broken connection in the tail light itself? It's a sealed unit and I don't want to break into to check.

I am by no means comfortable or knowledgeable about electrics so if I am missing something no matter how obvious please let me know.
I need to have the bike street legal by friday as I have a recall appt for stator sat. I'll drive without a brake light but would rather not.
Thanks for any help,
Cameron

Dang it, I never hit send on my edit earlier. I had more info for you besides the diagram.

When you say "entering the unit", do you mean the wires in the bike harness or the wires inside the tail light? Never mind the tail light's wire colors since they don't necessarily match what the bike uses.

I'm not 100% sure how to read their diagram, but from your description and the diagram it sounds like the two wires you have left over are the wires for the tail light (blue for steady and yellow for when applying the brake) and you've connected the turn signal wires to the tail light.

From what I see in the diagram it should be safe to try hitting the turn signal and see what it does to the tail light. My guess is it lights up.

-Todd

That sounds reasonable, except that I plugged into the same place that the old tail light was. I did learn that if you plug the two loose wires into the yellow plug you will blow your ten amp fuse. Blinkers work with white plug disconnected
First pic is the tail light plug.
Second is the 2 extra wires and you can see the plug that will short the ten amp fuse.
DSCN2623 by cam2hook, on Flickr" />

DSCN2622 by cam2hook, on Flickr" />

Don't tie the blue and yellow wires together if you don't know what they are exactly. At a minimum I'd wrap each one in electrical tape and then tape them together so they aren't just dangling around. Personally I'd use heat shrink if you have it. They should be part of a little yellow connector

Does the tail light illuminate if you use either of the brakes?

Check the resistance between wires on the tail light. I wonder if it's pinned out differently than stock. The stock should read some resistance between the top two wires and should look like an open between either one and ground (the bottom wire). If the new one isn't the same that could be your problem. By "top" it looks like the side with the tab.

I'm kind of at a loss here. The tail light isn't super complicated electrically but without having a bike in front of me it's hard to say how it's supposed to be wired. Mine came with an aftermarket tail light assembly and no plate lights. I added those lights but all the wires are now wrapped up in shrink tube and tape so I can't see the colors.

I'm not sure how to check resistance..The light does not work when brakes are used.

I was trying to explain (and not very well) that I matched the black and white wires on the unit to the hot and neutral on the factory plug and they matched up, so I guess it's pinned correctly, it should just be a plug and play. I might dig into the light, I sort of suspect something came loose inside, it was reasonably cheap, but hopefully I can open without screwing it up too bad.


Edit: So after thinking about I thought "What if they didn't pin it correctly?" so I cut the black and red wires and switch them. Viola, Tail light works, except I'm back to my original problem. It does not get brighter when brakes are applied, either front or rear, and I triple checked its not stuck on the "brake" setting. WTF? I'm starting to question my sanity here

Thinking out loud...

The three wires that go to the tail light are: regular on, brakes on and GND. If you have regular on working then the wire from the brakes has to be also correct.

I'm not sure eyeballing the brightness will tell you that it's the correct brightness. What makes you think you aren't stuck in the brakes on setting? What did you triple check? If you have the regular on and brakes on wires reversed the light would always be in the bright (braking) mode regardless of the position of the brake switches. In this scenario, when you hit the brakes it won't change brightness. If this is your problem, reversing these two wires would solve it.

P.S. When you're swapping wires around, I hope you're doing it on the tail light side and not mucking with your bike's harness.

P.P.S. Do you have the stock light handy to plug in and just make sure all the parts of the bike work?

lol Yes I am being very careful to not screw with the harness. As for brightness, I guess I just looked and thought all the leds were on. The stock light was doing the same thing, I thought it was broken (reasonable assumption, PO had broken into and re glued it) because there was no change in brightness. Now that I think about it more, this happened at some point after I went woods riding and several crashes, I also put a bunch of pressure on the brake lever trying to unbend it. Is it possible the switch got broken? Nothing is contacting it on the brake lever side of the house.

If you have a volt meter, you should be able to disconnect the tail light and check the voltage on the pins in the bike's connector. With the bike on one should be ~12VDC all the time and the other should ~0VDC until you hit the brakes, at which point they should both be ~12VDC. You might need some help with this so you can work the meter and brakes without accidentally touching the leads together and shorting 12V to GND.

Since neither brake makes the brake light come on, I doubt you have a broken switch unless it's broken ON, which you'll find by doing the measurement above.

Just for grins, give the wires going into the connectors a gentle tug and see if one is loose. You wouldn't believe how many problems are caused by things not being plugged in :)

I'm a little confused about how to check this. There are three pins on the plug. I can use the meter and I get 13v when I touch 2 (nothing with any other combo), so if I put on the brake I should see a reading from another combo?

kabulpostie wrote:

I'm a little confused about how to check this. There are three pins on the plug. I can use the meter and I get 13v when I touch 2 (nothing with any other combo), so if I put on the brake I should see a reading from another combo?

Right. I'm going to assume that the lower pin in the triangle connector is GND. When you measure 13v it's between that pin and one of the upper pins. When you measure between GND and the other upper pin (and the brakes are off) you should read ~0v (technically it's floating so it could be any voltage but if it's not 0v it'll approach 0v the longer you leave the probes on there). Anyway, when you apply the brake (I'd check both to be safe) you should now see 13v.

If that works, it'll tell you that the bike half of your circuitry is working and you don't have any damaged wires or switches. That isolates any problems/issues to the tail light unit.

All right, just did that and what do you know, apparently the brake switches are working as I got 13v from the third pin when applied. However this now makes me wonder what the heck is going on? Why would I have the same issue with two lights, one new and one old. From this test it has to be the light right?

By the way, thanks much for taking your time to help out, much appreciated!

It sounds like the issue is with the light or at least on the light side of the circuit. Have you tried swapping the two top wires on the light's connector? If they're reversed you'll be at full blast all the time and hitting the brakes won't make a difference.

You should be able to get them out of the connector without cutting anything. Usually there's just a little barb or two that hold the wires into the connector and you just have to insert something small in there to press them out of the way. Or even easier would be to take two short pieces of wire and use one to connect the ground between the two connectors and cross the other wire from the bike's harness to the opposite top pin on the light-side connector and see if the behaviour changes. I hope this explanation makes sense.

You're welcome for the help. I'm new to motorcycles but not new to electronics/troubleshooting so I'm just glad to be able to give back where I can.

Thanks, I'll have to try that tomorrow, it's been raining here and I have an outdoor workshop:)

You sir, are a genius, works perfectly now thanks so much for the help!

Awesome! I'm really glad that worked out and with a few hours to spare. Like I said before, I'm glad to be able to help.

-Todd