Best way to wire up a rear brake light on WR400?

11 replies to this topic
  • fix

Posted September 14, 2008 - 04:06 AM


The wr400 i recently bought was meant to have a rear brake light which had just stopped working,but after removing an alloy plate covering the rear brake servo there doesnt seem to be a sensor there (but there are two wires with spade connectors that arent being used)

In the past all my bikes have had a sensor that has a spring attached to the brake lever,when you press the lever it pulls the spring which turns the brake light on.

With the wr being an off road bike i cant see anywhere to mount a sensor,does anyone know the best thing to do to get one working?

I thought about maybe using tie wraps or after searching on here people use hydraulic sensors but i have no idea how they work or where to get one in the UK

Any help is appreciated thanks!

  • byggd

Posted September 14, 2008 - 05:15 AM


Does the switch look something like this?

I'm trying to figure out, if it was working and stopped what was it wired to before??

  • fix

Posted September 14, 2008 - 08:22 AM


No there isnt a sensor there at all just two wires hanging about,one goes goes the rear light and one into the loom somewhere.

If the sensor that youve put a link to will work with my bike ill buy one of them it looks simple enough

  • 5valve

Posted September 14, 2008 - 11:16 AM


the thing on the link is the pressure sensor. It is originally fitted to rear brake.
But you should have free connector for it under the tank if bike was ment to have the brake light switch.
position 3
ask your YMH dealer for this part

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  • fix

Posted September 14, 2008 - 12:46 PM


Thanks for the diagram

I dont think my bike originally had lighting out of the factory,the bike has an aftermarket led light fitted on the rear and an aftermarket headlight.

There is a wire from the rear light and wire from under the tank area that both have spade connectors that are hanging by the rear brake servo.

The servo definately doesnt have a hydraulic sensor in the top of it its just a normal bolt so its abit strange why wires are there but no sensor :excuseme:

But ive seen a sensor on a UK website just like the one in the link so will i be ok just using that instead of ringing Yamaha?

  • tcmII

Posted September 14, 2008 - 04:47 PM


WR400 rear lamp and socket is wired for the 1157 dual filiment bulb. The many people, including myself, have added a hydraulic switch like the one show in the link to add a rear brake lamp. The switch replaces the bajo bolt on the rear master cylinder (servo acroos the pond).

Using the two wires from the switch, one goes to the unused connector under the seat for the brake lamp, the other wire can be spliced anywhere in the the yellow wire that powers the headlamp and the tail lamp.

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  • fix

Posted September 15, 2008 - 04:06 AM


Sorry im just about to order a switch but im making sure i need a single banjo bolt

Is double two banjo bolts wired together one each for front and rear?


  • byggd

Posted September 15, 2008 - 12:50 PM


I've only seen them offered for the rear. I have never seen one for the front.

  • fix

Posted September 15, 2008 - 10:54 PM


I think the same banjo switch fits the front and rear,im gonna order a single banjo as i dont know what the double is for :excuseme:

  • trailhead2004

Posted September 16, 2008 - 12:12 PM


The double banjo switch would be used when there are two brakes lines coming off the same master cylinder (servo). Buy the single banjo switch.


  • fix

Posted September 16, 2008 - 10:17 PM


Ah i understand what you mean ive ordered a single banjo thanks :excuseme:

  • ColoWyo

Posted September 16, 2008 - 11:48 PM


I did this today to my 2000 WR400. Works great, so far.

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