Brake light issue

[Chuck]

 

 

The light only runs when braking. 

Uhh, that sounds normal?

[Cdogger]

 

The light only runs when braking.

Uhh, that sounds normal?

I think one filament is supposed to be constantly running.

[docc]

Correct, Tail Light is on with the Ignition Switch; Brake Light on with either of the front or rear Brake Light Switch.

 

Cdogger, could you restate what the filaments do 1) ignition on, 2) front brake applied, 3) rear brake applied?

[Cdogger]

1. Lights off completely

2. Both filaments on

3. Both filaments on

 

If I rotate the bulb 180° the same thing happens but only one filament turns on.

[Kiwi_Roy]

If the tail light won't go it's either the fuse or more likely a wire broken off the ignition switch. The switch is held on by 2 Phillips screws from under, take the opportunity to service it and when you put it back together fasten the wires to the switch so they don't flex at the solder joint.

Update

        Check for Voltage at fuse 6 with the key On, if not the wire is likely broken

As Docc mentioned the same wire feeds the Park light in the bucket.

[GuzziMoto]

You should be able to use a meter directly on the socket for the bulb. You should have power between one of the two center contacts and ground when the key is one, and the other should only have power when the brakes are activated. Removing the bulb reduces the chance of voltage feeding back to light the other filament.

I suspect docc is right, you have an issue with one of the two sides and the second filament is lighting due to voltage backing up that side. The question is, which side is duff.

[docc]

If the city light and instrument lights are on, it's really common that the bulb contacts inside the tail light get bent too far in. You can get hold of them with a probe or such and reshape them to make positive contact with the bulb.

 

Very common V11 failure.

[docc]

The "tag light" is also wired with the tail light. Very easy to see if the tag light is burning and the tail light is not.

[Kiwi_Roy]

A weird thing with the brake lights, they are fed from the headlight relay so make sure the Headlights on when you are troubleshooting i.e. the ignition must be On

 

The Tail light is on in Park or Run position, Fuse 6 Live

[docc]

A weird thing with the brake lights, they are fed from the headlight relay so make sure the Headlights on when you are troubleshooting i.e. the ignition must be On

 

The Tail light is on in Park or Run position, Fuse 6 Live

Hopefully, Cdogger's issue is as simple as the weak contacts inside the tail light.

 

But, there is this (*perhaps* not directly related to Cdogger's tail light):  I have always thought Fuse#6 is fed from the Ignition Switch and there is no relay to the tail light, tag light, instrument illumination, and *city* light (all together, I would call these the "running lights").  That's the way it looks on the wiring screamatic.

 

So, I just wired in my new Speedhut gauges and used the existing gauge illumination wiring to light the faces. Pulling Fuse 6, I expected the faces to go dark, but *NO* - they stay on. Along with the tail light/tag light/city light ("running lights")! All on with no Fuse 6.

 

It was late and I managed a fitful sleep with awkward dreams of crossed wires and *what-could-I-have-possibly-screwd-up*.

 

What I came up with: pulling the Headlight Relay (#2). All the other lights go out and the "running lights" stay lit.  With no Relay#2, pulling Fuse 6 extinguishes the "running lights" as expected.

 

Apparently, there is a redundant circuit that lights the Running Lights if there is relay failure. Yet, the Running Lights also get lit through Relay#2.

 

But how? I don't see that on the screamatic . . .

[Cdogger]

UPDATE

OK so I just replaced the front brake switch and figured out that the switch actuator (little black plastic cylinder) had gotten smooshed (probably from an impact on that lever from my aunt running into the garage before I got the bike) and wasn't hitting the switch. Both switches work now. Here's the important part.

 

When I am not touching the brakes the tail light is dark. When I push the brakes one or both of the filaments turn on depending upon the orientation of the bulb. I measured the voltage of the two prongs that make contact with the bottom of the bulb with my multi-meter and found out that the right side prong never has any voltage. The left side one which I think is working correctly has no voltage when the brakes are off and about 12 volts when the brakes are on. So whatever wire comes to that prong is broken somewhere I think?  

[Scud]

That's good logic. I think your next step should be to remove the tail light assembly from the rear fender. Notice how all the wires are connected, then pull everything and test voltages at the connectors. If you see power, clean the connections and reassemble. If not, chase the wires further back into the loom.

[docc]

Hey, is the tag light on?

[Cdogger]

Hey, is the tag light on?

Yes it is. I actually just had to replace that bulb too. Kind of a pain to get in there.

[Cdogger]

Aha! I found it! There a snapped wire coming to the right contact. Looks like more rodent damage. I'm just going to use those pinch type connectors and then electrical tape around it.