Brake light works, tail light does not

1982 XJ750 Seca. The tail light does not illuminate when the bike is on, but I do get a full brake light (all filaments) with both front and rear levers.

What gives?

 

You have wiring problems, possibly a bad ground to the tail light assembly. Both sections of the bulb are not suppose to come on when the brakes are on, only the single bright filaments.
Also check the bulb sockets , rust and dirt in them prevent the bulb from grounding.
Have you had the tail light un-wirred and out of the bike? Your problem could also be the 3 wires are hooked up wrong.

 

Oh, ok. I thought one was always on, then both came on when the brakes are hit.

I have not had the wires out of the bike. The tail light worked properly, then didn't. I'll check for corrosion first, but where can I locate the grounds? Just follow the wiresback . .?

 

Solid black wires, usually "commonly" plugged, are ground wires.

The problem may very well be in the headlight area where all of the turn signal wiring originates.

 

Crap, I hate the wiring side of things. Guess I gotta work on it to get better at it.

Thanks for the help. I guess I'll be tracing black wires if it's not a dirty plug.

 

"Oh, ok. I thought one was always on, then both came on when the brakes are hit. "
this is right, one comes on when you turn the key, the other when the brakes are on. brakes on two filaments, brakes off one filament

 

You were thinking right the first time Polock. The running light(dim) and the brake(bright) are operated seperatly. The brake should NOT light the running part of the bulb unless there is a problem.

 

Thanks guys. I guess I didn't really need to ask here before digging in. I followed a good line all the way up to the headlight basket, where I found a rats nest of non-terminated wires.

I'll be cutting and splicing things back together today. I don't know what the tail light issue was, but I'm surprised it was my only one. Oh, besides not having lights on my gauges. Maybe those will come back on too!

 

I am having a similar issue. except my brake light is always on. my signals don't work neither does the neutral light. what I remember the guard lights don't come on until the bike is running just like the headlight.