Tail Light is out, what to do?

Alright so I was riding in the rain home yesterday in the rain. Well I went to ride today and the rear tail light is out.


It does not respond to the hand brake or rear brake and doesn't light up at all. The front left and right signals work as well as the headlight Hi/Lo.


It looks as if it was modded some way. I have looked all over google and the forums and have not found a situation similar to mine.


Heres what it looks like. Could anyone tell me what is going on here? Is the board fried, a fuse somewhere?







Thanks in advance!

Are you comfortable with a meter? Check voltage on the power wire coming in. Verify you have continuity to ground. If no power is there then id suspect a fuse.

Not exactly, I went out and bought a cheap one today. If you could guide my in the right direction on how to use it that would be awesome. I have looked up online how to use it but I am not really sure how to apply it to this situation.

I checked my fuse box and they were all in working condition. are there any other fuses i should check?

my front left and right front blinkers work as well.

Could you take a better picture of the wires at the tail light? There are probably 3 wires your looking for. Theres going to be a ground, running light power, and brake light power. Ground should have continuity to ground at all times. Your meter should have a ohm sign where you would check resistance. Youll have to look up what the ohm sign is because im not sure how to type it. In this mode the meter checks the resistance to electrical flow between whatever the 2 meter wires are hooked to. Always check resistance with the motorcycle power OFF. One of those wires should have 0 ohms or close to it to ground. You can use any bare piece of metal on the frame of the bike for a "ground" source for your black meter wire. For checking the wires you can either poke through the wires instulation or cut/disconnect the wires at the tail light.

The running light wire will have 12v or so whenever the key is turned on.

The brake light should have 12v whenever the brake is engaged.

Get a picture of the wires and well try to figure out which one is which.

If both the tail and brake lights are out, I'd suspect a ground issue.

Where would the ground be located? Is there a common area that people ground to commonly? I searched for it on the bike and only found one on top of the lower half of the engine.

I will be back to my bike in a few days.

ST723 wrote:

Where would the ground be located? Is there a common area that people ground to commonly? I searched for it on the bike and only found one on top of the lower half of the engine.

I will be back to my bike in a few days.

You have the stock tail light and wiring harness, correct? If so, the ground is one of the three wires going into the tail light. One positive for the tail, one positive for the brake, and one ground (essentially a return path for the positive current being fed to the tail or brake light. That's about as simple as I can make it.

If one light, or the other, functions; you know the ground is intact because the ground provides coverage to both lights - so neither could work if the ground wire was broken, corroded, etc.

Just check the wires. In the picture you posted it looks like someone went nuts with heat shrink tubing; I'd cut that off and ensure the connection it was designed to protect is still a connection.

To specifically answer the "where to ground" question - the negative terminal of the battery, any frame component that is steel and is not insulated from ground by paint, rubber, or any other insulator - although this frame is aluminum so you won't get a good ground there.

Thanks for everyone the help!


I did all of the above checked everything with my multi-meter and everything checked out fine.

I finally broke down and just cracked the tail light open. Turns out that the ground wire solder was broke off the board.

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everything works with the ground re-attatched!

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Now the problem is sealing back up the plastic housing? I didn't have a dremel so it was a barbaric opening.

I am think silicone glue around it?

Thanks!

Yeah, RTV silicone would work fine.