I have recently bought my first motorcycle, it's a 1992 gs500e. I love the bike but being over 20 years old there are some small issues. The one I'm most concerned about is my taillight; the taillight doesn't light up when the lights are on but lights up ONLY when the brakes are applied. This means it's illegal to ride at night or really anytime and it's also a safety hazard. I'm wondering if anyone has any idea what it could be. P.S. the blinkers front and back along with the headlight all work.

 that bulb is a 2 filament bulb im willing to bet one is blown. the running lamp side. willing to bet with a bulb replacement. problem will be solved

thank you for the response. I will go buy some new bulbs for the tail light and since they're so cheap i'll just replace both and hopefully that solves the problem.

i know when i blew the running light side of the filament on my first gs i had to barely hold the brake to activate the brake light side to get home one eve. bulbs are cheap and can be purchased in auto parts houses too. let us know if this helped out. it seems the likely culprit.
Aaron

.... buy the good/better bulbs! .... the cheap ones are just that! ... this bike is very vibration prone and from my fiddling with various bulbs/positions.... the quality bulbs are worth it long term!

Any recommendations for decent bulbs?

Quote from: Janx101 on September 17, 2015, 04:25:09 AM
.... buy the good/better bulbs! .... the cheap ones are just that! ... this bike is very vibration prone and from my fiddling with various bulbs/positions.... the quality bulbs are worth it long term!

agreed janx didnt mean grab the cheap stuff. cost difference between cheap and quality is minimal. worth it for quality imho

Well its not the bulbs because I just checked them and they both light up when both brakes were applied. I'm thinking its something to do with the wiring.

My 92 had this exact same issue. It came down to the front brake light switch being a little corroded. I took off this switch and sanded down the contacts inside it and it worked again.

If you have a multimeter you can easily trace where the 'signal' gets interrupted.

Ok thanks, I'll try to get around to it and hopefully it works.

Are you sure it works? If it comes on and off when you hit the brakes (either the front or rear), the brake filaments are fine. The regular running lights are a second filament inside the same bulb.
If you have a multimeter, check for resistance/continuity between the outside contact and the two inner contacts.

https://www.youtube.com/watch?v=X84vEfkjb9s

I did not know that, thanks for the info and the detailed video.

easy way to check filaments is to remove bulbs hold up to light you will  see broken filament. im like 99 percent sure this is the culprit. 2 filaments side by side. when you turn power on with key the circuit will energise   the running light filament. when you squeeze break levers, the other filament will energise and glow.
Aaron

philly, I JUST this happen to my headlight after seeing it on the brake light several months ago.

Change the bulbs. As yam and ed said, it really is probably just your low beam filament.

Or you could take the opportunity to order some LEDs and lower the load on the electrical system.

https://www.superbrightleds.com/moreinfo/motorcycle-led-bulbs/1157-led-bulb-dual-function-25-led-motorcycle-bulb/170/767/

so both filaments work but its something in the wiring. When I took out the bulbs to check them (they were fine ) but when i put the bulbs back in i had one upside down the the other filament ( running light )lit up and stayed lit indicating the bulbs were fine but there was something wrong with the wiring. I'm thinking that maybe i could just upgrade the fixture to an L.E.D tail light and hopefully that fixes it and if it doesn't then there would be more wiring problems within the harness leading to the tail light. what are some thoughts on that? and if anyone knows of a tail light that'll work could i get some info.

If the power isn't getting to the back, you'll need to fix the wiring for an LED tail to work.

Check out the wiring diagram, you'll want to probe the brown wire for power, trace it back until you find 12V.

http://bbburma.net/Scans/Haynes_WiringDiagram_US_90-96.jpg

there ya go