Brake light/high beam wiring issues

[eghansen]

Got a 1975 XS650b with some wiring issues. I figure there's a mix-up somewhere and I'll need to trace the wires but wanted to ask to see if it could be more complicated. I can post some pictures tomorrow.

Brake lamp (LED bulb)

Key on, lights off: glows dim (3 diodes lit), when either brake is pressed the light turns off.

Key on, lights ON: glows bright (all diodes lit), neither brake has any effect.

Brake lamp problem indicator always blinking.

Head lamp (not stock)

Low beam: actually high beam (high beam indicator light is on).

High beam: blows main fuse instantly.

 

[eghansen]

Update... I switched to a regular, non-LED, brake lamp bulb and got completely different symptoms.

Brake lamp (regular bulb)

Key on, lights off: no light, neither brake has any effect.

Key on, lights ON: one filiment lit, neither brake has any effect.

Brake lamp problem indicator OFF.


Seems like a more straight forward issue now. But why did the LED bulb turn off when the brakes were applied??

According to this diagram it looks like it could be a blown 10 amp fuse (the horn also doesn't work). BUT... If that's the case, and if the diagram is correct, the neutral light should be out too... and it's not.

I looked for the 10 amp fuses and couldn't find them. A PO rewired things to use an inline 20 amp fuse. Did this replace the 10 fuses as well?

 

[jayel]

why did the LED bulb turn off when the brakes were applied??

short to ground or cutting power to light, the main fuse was a 20A, secondary circuits 10A

 

[XSLeo]

If your wiring is stock, the light checker needs a stock bulb to work right. The led bulb draws much less current. This makes the light checher think the bulb is blown.
If you have it wired like in that diagram, the headlight and tail light are on totally seperate circuits from the brake light.
My guess would be weak/bad grounds.
I have my 75, with Led tail/brake and turn signals wired like that diagram and everything works great.
I would go through the wiring and be sure everything is hooked up right and has good grounds.
Leo

 

[eghansen]

The wiring isn't completely stock because there's a blade 10 amp fuse.. but yeah, I'm going to avoid the LED bulbs regardless.

I wasn't suggesting that the headlight and brake lamp were connected.. just 2 separate issues. I was suggesting that the brake lamp and horn were connected. But if the diagram wiring is correct, and the neutral indicator is indeed on the same circuit, then maybe not.

I found one ground wire that is cut.. just a matter of tracing where it's supposed to go. Also the wire bundle headed to the tail light and rear signals might be a bit funny. I'll try to get a pic.

Thanks Leo!

 

[XSLeo]

If the only mod to the wiring is the fuse, then the brown wire after the switch is the main power wire for the bike. It sends power to horn, neutral light, brake light switches, engine stop switch, regulator, and the turn signal flasher.
The diagram you post is a universal simplified diagram. If yours is pretty much stock it won't match that diagram.
In the tech section, in the wiring diagrams thread you will find a stock diagram. Jayel even colored it.
The LED lights are a great savings on current draw. The less the lights draw the better the battery stays charged.
Leo

 

[eghansen]

Turns out everything was caused by bad wiring in the headlamp. Took a couple hours to sort out (not by me!).

 

[Jawknee21]

I got the same kind of problem. No brake when lever is pulled...

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[XSLeo]

Jawknee21, Same problem? His was goofy wiring. No brake when lever is pulled sounds like your brake need at least bleeding, if not flushing or rebuilding.
Or do you not have a brake light light up when you pull the lever or step on the pedal?
Leo