Brake light issue troubleshooting

7 replies to this topic
  • Wounded Lobster

Posted July 16, 2014 - 01:22 AM


Hellooo! Just got my new regulator so trying to get all my lights up and working.

I have running indicators, headlight, tail light even but my brake light will not light up!?


The globe is fine. I first tested at the plug under the seat and I do not get current on the brake light pin by pulling either brake lever.


I then tried bypassing the front switch altogether by running a wire across the terminal it plugs into behind the headlight but still no dice!? Surely that should have lit it up?


Any ideas? A ripped/cut wire along the way seems unlikely but its about all I can think of.


Seeing as neither lever works could the problem be located where they share the same wires?


Any and all help much appreciated, thanks!

  • Thommo_400f

Posted July 16, 2014 - 04:36 PM


What bike?

Check the actual switches. Put a multimeter across both wires to brake pressure switch and push brake lever to check continuity. Do same for front brake switch.

  • Wounded Lobster

Posted July 16, 2014 - 05:46 PM


Thanks for the reply!
Sorry, 04 WR450, they come road legal from factory here in aus I think it's different elsewhere?
I figured if the switch was the problem bypassing it at its plug would have fixed it? I will check anyway.
Gonna be out there all day with a multimeter.

  • Wounded Lobster

Posted July 16, 2014 - 07:41 PM


No continuity with lever pulled. Bypassing the switch by running a wire between the plug terminals does not create current. There is about half a volt between the two plug terminals. This means it must be a bad connection somewhere between the battery and that plug, right?

Thanks again.

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  • Thommo_400f

Posted July 16, 2014 - 08:03 PM


The brake light circuit is a pretty simple one. Just gota get it sorted in your head so you can test it correctly.




Diagram shows a common relay, but yours might just be a common joint. "Basically" same for all bikes.


Work you way through, you'll get it eventually



  • Wounded Lobster

Posted July 16, 2014 - 08:15 PM


Thanks for the diagram. Haha yep I thought I might be testing wrong.
I'm thinking about just rewiring the front plug to the battery + on one side and brake light + on the other. That will 100% fix any problems unless it is a grounding issue.

  • Wounded Lobster

Posted July 16, 2014 - 08:56 PM


Fixed! Pulled some un-factory-looking elec tape off and found that some turkey had cut the brake light+ wire at the rear plug!? :confused:   Reconnected and its all working fine now on both levers. Thanks for the help, that diagram is actually different to what I had assumed it would be so im glad you posted it!


EDIT: and please excuse my shameless double posting habits

Edited by Wounded Lobster, July 16, 2014 - 08:56 PM.

  • Thommo_400f

Posted July 16, 2014 - 08:58 PM




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