Help with lighting and brake switch sensitivity.

[iamjeromy]

Hey guys, I'm not much of an electrician, so I am reaching out for a little help on this one. A few different problems all related to the same part(s) so I broke them up by paragraph.

My brake light won't glow while the bike is running/on, but when I push the brake the light comes on. (I am not running front brakes, so this is the rear only) Release brake, total darkness... can someone help me figure out how to make it stay on all the time, of course with the increased brightness while hitting the brake.

Another thing I would like to know. Is there a way I can increase the overall intensity of the light so that I can be more visible to people behind me?

Also... I desperately need to increase the sensitivity of the brake light switch. I have to smash on the brake to the point where I am almost skidding for the damn light to come on. This madness has to stop! No pun intended...

[BrokenSprocketGarage]

Year/make/model? What type of tailight? Hydraulic or mechanical rear brake?

[iamjeromy]

It's a 2000 Sportster with a side mount license plate/taillight. It's the 'stop' Model A style taillight. It's the stock brake system from the 2000 Sportster, so should be hydraulic.

[mattressking]

So the stock taillights/turn signals have a lot of wiring. The only wires you need off of it are as follows:

Blue - Running lights. This is the one that needs to be hooked up to your taillight.
Red/Yellow - Brakelights, however it sounds like its hooked up correctly since it is illuminating when you press the brake.
Black - Ground

Your new taillight should have 3 wires. One is power for running lights, one is for brake lights (which sounds like it is hooked up correctly) and the last is ground.

Since your light is grounded and getting power for brake lights, take the remaining wire and connect it to the blue wire. If you would like to check for functionality prior, connect a lead to the remaining wire to battery + and the lamp should light up. The dimmer of the two functions is your running light, the bright light is your brakes.

You might have to swap the wires around to get the running light as the dimmer light and the brake as the bright light.

[bobberadam]

Just a thought, start with the easy stuff, Are both filaments of the bulb good, Maybe the running light filament is burned out? Is this the same one that was on the bike when you got rear ended?

[XFatTonyX]

Agreed, check the bulb first. As far as intensity of the light goes, Is it a black housing inside the light? If so get some aluminum reflective tape (Harbor freight has some cheap) and cover the inside of the housing behind the bulb. Typically doubles the light output compared to the black housing.

Also pick up a test light if your bulb is good.
Blue obviously should have constant power
red / yellow on only when brake is depressed (should be working already like mattressking said)
Black should also be good since brake light is working.

Looks like the brake light switch is a hydraulic pressure switch so you probably need a new one and a rear brake flush and bleed. Might be able to clean it but you'll still need to flush and bleed the system

[Guest]

Yah make sure it's a double filament bulb you have in it first. The on with ignition switch can be tapped into any on with IG switch power... but NOT the one coming in through the brake switch... that one only has power with the brake switch unless you tap into it before it attaches to the switch.

You can shorten the spring a tad if it's a pull type on type or adjust linkage of it's a push on type... but many switches have a screw body allowing adjustment of the whole switch itself by twisting it in it's threaded mount clockwise or counter clockwise. I dunno what switch type, so trying to cover them all... if you have a ton of fucking pedal play and it's a drum brake? Probably worn shoes making the drum arm/rod and pedal travel a good amount to compensate missing pad material... messing up the contact when pressed...

If that's the case, and no other adjustment is cutting it, you can unhook the drum arm from the drum pin and move it a couple of splines so the arm is a little more forward if a brake rod adjustment isn't taking up the slack. (always remove bolts completely from adjustable splines before removal on drum arms/kickers etc. to avoid strippage)... I personally don't like my brake pedal to have travel further down than being level with the peg surface... dipping past the peg just needlessly works the calf muscle too much, and also translates to a slower braking time, because it doesn't match response time.

[iamjeromy]

@bobberadam Yeah, it's the same bike from when I got rear ended. It used to work before, but doesn't after the fact. I never did bother to check the bulb. Could be the culprit.

@JetBlackll The brake itself works as normal, it's just that the brake light switch won't engage until you are way into the meat of the brake. I want it to come on when I barely touch the brake. I will play with some of your suggestions. I haven't taken that assembly apart, ever. So I may look up some diagrams before wrenching it apart. Brake line flush doesn't sound like a bad idea either.

[BrokenSprocketGarage]

Needs a new brake pressure switch if you have to stomp on it to get it to work

[iamjeromy]

Ok so the running lamp bulb was bad, and some wiring had come loose somewhere down the line from the crash/towing, etc... I was in the process of putting it all back together and dropped the red glass lens (Ford Model A style 'STOP' light) and broke it, lol. So I had to order a replacement and I'm now waiting for that. The only thing to tinker with now is the brake pressure switch.