[P51Pilot]

Can anyone tell me why the brake lights are wired through the anti-dive valve on a '94 Ultra Classic? My brake lights stopped working and I traced the wires back to see if I could find the problem. When I unplugged the plug that connects to the anti-dive valve, I found that by putting power to the red wire with a yellow stripe, the brake lights came on. The other wire appears to be a ground. Doesn't make sense to me. If the valve is bad, could that cause the brake lights to not work? The service manual says that when you turn on the ignition, you should hear a faint click at the valve. I don't hear or feel anything at the valve. The brake light relay clicks when the brake pedal or lever is applied. Any idea what my problem might be?

Thanks!

 

[DrHeathenScum]

hmmm, red w/yellow is your brake light wire... by putting power to it, the brake light should light up.

check the accessory fuse and also the relay under the seat that clicks when you apply the brakes... I'd guess your problem is in there somewhere.

I'm not very familliar with the wiring system on your bike, but if you have a diagram, see where the red/yellow wire runs and is powered from. It should be off the brake light relay.

oh yeah, the anti-dive valve would be powered by the brake light circuit... anti-dive when brakes are applied.

 

[P51Pilot]

Fuse & relay

The relay is located under the fairing and I swaped it with another one of the same size. Still no brake lights. Also checked the fuses. They're all good.
As far as the anti-dive valve goes... by applying the brakes, the valve is activated? That's why the brake light wire runs to it? Okay... that makes sense now. If the valve was bad, would that affect my brake lights?
Otherwise I'm still stuck on why I have no brake lights. Relay works and the fuses are good. I also checked the brake light switch for the rear brakes, and it's working okay. Even if it was bad, applying the front brakes should give me brake lights. I'm stumped. Thanks for any help.

 

[DrHeathenScum]

tough without a wiring diagram or having the bike in front of me...

if you apply power to the red/yellow wire at the anti-dive valve, the brake light does light up... that rules out the bulb. BTW, never a good idea to do stuff like that. If it was controlled by a computer, you could have toasted it.

a bad valve should not be affecting your brake lights in this case, as long as it's not shorted and taking a fuse out... you did check ALL the fuses, right?

check the wires at the relay... there should at least be a red/yellow and probably an orange/white. The orange/white should have power with the key on. Look at the relay, there's usually a pin-out schematic on the side... see which terminals are switched. Standard relay's have the terminal labeled 30 powered up to switch power out to terminal labeled 87 (see "Bosch Relay": http://www.bcae1.com/relays.htm).

Let me know what you find.

 

[P51Pilot]

Fuses

Yes, I did check all the fuses - those under the fairing and those under the left side cover.
I'm heading out of town - will be back Monday evening to check out the rest of your suggestions. Thanks for the help - will advise what all I find. Thanks!

 

[P51Pilot]

Hats off to the Dr.

When I checked the brake light relay the first time, I only checked it to see if it clicked when I applied the brake pedal. It did.
Thanks for the info on Bosch relays. When I checked which terminals had power, I found the problem - bad relay. It was clicking, but not energizing one of the contacts. Replaced the relay with a new one and now I have brake lights. That was simple, wasn't it? So thank you very much for your time and help. It is all very much appreciated.

 

[DrHeathenScum]

When I checked the brake light relay the first time, I only checked it to see if it clicked when I applied the brake pedal. It did.
Thanks for the info on Bosch relays. When I checked which terminals had power, I found the problem - bad relay. It was clicking, but not energizing one of the contacts. Replaced the relay with a new one and now I have brake lights. That was simple, wasn't it? So thank you very much for your time and help. It is all very much appreciated.

glad to help!