Tail light stopped working brake light still does

AJWatUC

Been Around the Block
My tail light doesn't work but my brake light does. Whats weird is the tail light works when I turn the key to acc.
PLEASE don't say check the bulb The bulb works!!!!!
When I say Brake light I mean the filament in the bulb that gets power when I hit the brake.
When I say tail light I mean the other filament in the bulb that gets power when you turn on the lights.
What I know is the power wire from the tail lamp goes to the ignition so it seems to me the ignition is at fault.
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

according to wiring diagram it says the brown wire goes to combination(ignition) switch green yellow goes to rear stop switch (brake pedal) green goes to ground
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

is it possible there is a connection in the ignition thats not working? Im thinking this because the brown wire is the one not getting power when the lights are on but it gets power when I turn the ignition past on but that in turn turns out the headlight and stops the break pedal from turning on the brake light
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

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 ;)
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

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
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

I guess I had a lot of fill unnecessary info. So I will try to simplify it. I tested the brake light bulb both filament work. The problem is the tail light doesn't turn on when I turn on the lights. like it should. However the wire has power when I turn the key in the ignition to acc
Bert Jan said:
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 ;)
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

I
Captmilk76 said:
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
I tried that
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

Trying to wrap my head around what you are saying so lets use these terms.
Tail light - the regular illuminated part or your rear lamp, what comes on when you turn the key.
Brake light - (stop light) The second part of the rear lamp that only illuminates when you depress a brake (front or rear)
Key On - where the ignition switch is normally set to run the bike
Accessory - the key position that will allow minimal items to work but the engine will not start.

Now not being a dick but "break" to me means something is broken, "brake" means to stop.

Just to verify, you are asking why with your Key in the ON position, your brake (stop) light doesn't come on when you hit the brakes (front or rear) AND your headlamp is on.

If your headlamp is OFF you may have your key in the ACCESSORY position OR you have your headlamp switch in the "PARK" lamp setting. (my CB350F had that option)... either way I doubt the brake lamp will work.

Some rear lamps use the lamp housing mount istelf for the ground and only have two power wires, one for tail and one for brake. Is the third wire you added to provide a ground?

I want to help but am really confused with what is going on.
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

@ 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 ;)
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

Bert Jan said:
@ 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 ;)
Ok the brake lights lights up and the tail lamp lights up so both filaments in the bulb light up so obviously the light bulb works and gets power. The problem is the tail light should come on when i turn on the lights and it doesn't. However if i turn the key to acc the tail light will come on but nothing else comes on. this is why I'm wondering if its the ignition itself is bad. because the problem wire goes from the tail lamp to the ignition switch but when you turn on the lights the tail light doesnt come on so Im thinking maybe there is a short in the ignition switch.
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

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 lights


This 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.
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

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
 
Re: brake light stopped coming on with headlight it still comes on w/ brake

Bons said:
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

Bert Jan here again, now my GFs was logged in on my laptop in the workshop.. haha digital mayhem nowadays...
 
Bons said:
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 lights


This 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.

1973 Honda CB 500 four
 
If you get lights everywhere else (headlight, dash/gauges, etc.) with the ignition switch in the ON position, it's not likely going to be a bad ignition switch.
Can you post a link, or a pic, of the wiring diagram?
 
Hmmm, interesting...
Is this your wiring diagram?
http://www.oregonmotorcycleparts.com/Diagrams/CB500.pdf

If so, it could actually be a bad ignition switch. You can check for sure with a test light.
 
Tail light stopped working brake light still does

I noticed the gauge lights aren't working either. I don't have turn signals but if I wire one up comes on but doesn't blink



1973 cb500 four
 
Do you have a test light? You can check the circuits to see where power is going in but not out. That'll tell you what switch/connections is the problem.
 
finally had some free time today took the headlight out to check the wiring and what do ya know the wiring was disconnected. Easy fix... Thanks everyone for the feedback
 
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