First First of all - You can not always SEE if a lightbulb is broken. You want to know for sure, so hook up a battery straight to the lamp. (No wires or other junk in between.) and see if it burns. First of all, you state you have a 2-wires light in, right? How can you have 2 filaments then? 2 wire light has one negative (the metal on the lamp) and one positive (the solder on the back), making 2 connections e.g. 2 wires.When you have a dual filament light, you already have 2 (positive) solder points AND the metal from the lamp (negative)The original brake light has 3 wires. Brown, Green/Yellow and Green (negative). The Brown and Green/Yellow wires are never supposed to touch each other (besides thru the wolfram in the light). When you'd run a 'normal' light (1 earth and 2 positives) they would'nt touch either. My money is on a long-term shortcut that finally found it's way to destruction. Could be i'm missing the point but your explanation isn't that clear either
I have an xs650 but I just had a similar issue. I checked the contacts where the bulb contact the plate that the wires connect to and it wasn't pushing back on the bulb enough. (if that makes any sense to you) The plate must ave got a little wedged. This is in my Lucas style brake light
@ Hoosier:Parking light on old cb's lit the tail light and the little light inside the headlight (12v 6w) Brakelight dont work when ingition is on parking.Like hoosier states:If the lock has multiple choices (off/on/park) try them all and see if the brake light will come on. If your bulb has both wires intact, and there's power going to the main taillight wire and power to the brakewire when you apply the brake, it's simple. The bulb in not touching the wire inside the lightholder. If it did, it would light up Have you taken out the lamp and tested it on a spare battery or batteryloader? Thats the only way to be sure the lamp is good. Like they say, a picture says a thousand words. It would be appropiate here
Did you figure it out already? If you tell us wich bike it is, i could check the wiring diagram and that would clear things up i guess
Right, now we're talking! your post is somewhat confusing, as it says your brakelight wont come on, but ok...It normal for the taillight to come on when in ACC. There's a little light inside the headlamp that should also come on in ACC, but whatever, thats not important.As your taillight is coming on in ACC, it gets power from the ignition lock. Therefor, There must be a broken wire or corrosion in the headlamp bucket.ACC is the parking light. You dont need it and it sucks because there are extra wires at the ignition lock and thats confusing. The only thing the ignition lock needs to do is connect red wire to black wire. Black is positive on Honda. (assuming its a honda?) it also switches brown and white/brown, purely for the parking lightsThis should be between your main lights on/off switch and the ignition lock. I think it's not in the ignition as the taillight is switched in the handlebars, not in the ignition lock. When the bike is 'on' the taillight gets power from handlebr control. When in ACC it gets power from ignition lock.What bike are we talking about anyway?edit. It's Bert Jan here, my GF was logged in.