'03 Road King Taillights constantly on??

[Ranger74]

Thanks all for the advice - what a greta place to get info from fellow Harley Riders. I'm going to track down the glitch like we're tracking terrorists around the world right now - pretty successful I might add. I'll post again when/if I find it.

De Oppresso Liber
Ranger74

[HarleyCruiser]

Originally Posted by Ranger74

Does the back light burn both filaments with a lower voltage and then applying the brakes adds more voltage, thus a brighter "brake" light? or does one filament burn constantly as a running light and when brakes are appeared power goes to the 2d filament?

hanks for the assist.

They are separate. The running light is on the dimmer filament on the bulb the brake is the bright one.
The current goes through a fuse, to both brake switches and then to the bulb then to ground.
If either switch is stuck on the brake light will stay on.
You could also be getting feed back through the tail light if the ground is bad, but to me it sounds like you are getting feed through a bad brake switch.
Like I said unhook the rear switch first, see if that helps. That is easy, then next is the front. This is harder.
Get one of those 12v ice pick power checkers, looks like a ice pick with a wire coming out the handle and see if you have juice on both sides of the switch, when the switch should be off, if so the switch is bad.
You could also be getting juice through a short someplace from a hot wire, but that is not as common.

[hotrodsporty]

cruiser, a feed back through the ground wire is highly unlikely, sience you would need a source to ground to light the lamp, and if you get feed back though ground, where would you get your new path to ground? The pick power checkers are a simple way to check if voltage is there but a multi meter (fluke) would be the best.

If you have constant voltage on the brake filiment then there is absolutey a short from the brake wire to a direct + lead.

Start at the light and work your way forward.

[fxst04]

Try unplugging the brakelite switch. Check the switch with an ohm meter. Any reading at the switch is either a bad switch or pedal is not retrating.

[Wrightturn]

Good evening,

Bleed the brakes. Front first. This happens on the front most often.

[HarleyCruiser]

Originally Posted by hotrodsporty

cruiser, a feed back through the ground wire is highly unlikely, sience you would need a source to ground to light the lamp, and if you get feed back though ground, where would you get your new path to ground? The pick power checkers are a simple way to check if voltage is there but a multi meter (fluke) would be the best..

I did not say a feed through the ground, I said,
“You could also be getting feed back through the tail light if the ground is bad, but to me it sounds like you are getting feed through a bad brake switch.”
If the ground is bad then you get the tail light feed going back through the brake and both come on. They will both go off when you put the brake on.

Originally Posted by hotrodsporty

If you have constant voltage on the brake filiment then there is absolutey a short from the brake wire to a direct + lead...

That or more likely you have a brake switch stuck on.

[HarleyCruiser]

Originally Posted by HarleyCruiser

I did not say a feed through the ground, I said,
“You could also be getting feed back through the tail light if the ground is bad, but to me it sounds like you are getting feed through a bad brake switch.”
If the ground is bad then you get the tail light feed going back through the brake and both come on. They will both go off when you put the brake on.
That or more likely you have a brake switch stuck on.

Correction, I’ve Been thinking about it, don’t know that I have ever seen a brake light being fed from the tail light because of a bad ground. The brake light circuit would be open, so no ground, no feed back.
I have seen the bright element fed from the running light, and back through the turn flasher as a ground, when the bulb had a bad ground.
Don’t know why it would be a ground, must be something to do with the flasher option.

[hotrodsporty]

Cruiser, I agree, being fed from either tail, or other. And a brake switch is a great place to start. Good luck with the problem.

[Wrightturn]

Had this one twice. Both times front switch was stuck.

01 RK had set up for several years. Brake light worked after bleeding front brake.

05 Sportster after bars were changed and brake line replaced. Same result.