My brake light works, but my tail light does not function..

Hello, My '90 Intruder has some issues in that my tail light is not functioning, however, my brake light works when applying either brake. The bulb has been replaced, I had even taken it to a shop prior, had it fixed and she's having issues again. Is there anything that it could be that I can take care of myself?
Thanks,
Jason

Firstly whar did they fix or replace and do you have a voltage meter?

I believe there are only 3 wires to the combination running/brake light, one earth and two live wires. What did they fix or replace and do you have a voltage meter? It does sound like a corroded connection from what you have said

I would have the rear light apart and clean the connections, do the same with the handlebar light switch and then put a dollop of Vaseline in there and all around the connections.

Dodgy earth? Check for any moisture, signs of cable fraying or poor connections, then as Mr I says, add some vaseline. Hope you get it sorted.

The rear Brake/light combo is made up of a single earth and 2 lives so the earth at the bulb is good. However the live may not be good at the bulb but it is a very simple wiring system that is easily followed so if cleaning the connections doesn't work a volt meter is required to see where it is ending.

Thanks, I've got the night off so I may try tracing it back. Also, my receipt from the shop says, "wire coming out of ignition switch had came out of the connector, pushing the connector back in and taped the wiring back together." I will take a look around the wiring as well...

Yeah you can bet the issue is in the same place, let us know how you get on.