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1978 dt250mx rear brake light switch

G Digger

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Hi everyone

I am trying to connect the rear brake light switch and the linkage from the brake light switch to the rear brake pedal has got me scratching my head a little.

it is the linkage from the spring that returns the brake light switch plunger to normal after the rear brake has been released,

there is a fixing that fits on the rear of the pedal with a connecting rod on it to connect the spring, no matter which way i position it the movement is the wrong way.

it has been a year or more since i dismantled it and i am not sure this is even the right bit as I cant find the linkage on cmsnl.

a photo of someones linkage would be appreciated.

or a photo of where the springs attaches to.

I hope this makes sense

cheers Graham

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hi Graham


Not sure if this helps but this is my 1978 DT175MX rear brake light set up.


 and the other end of the spring goes on the top part of the brake pedal



the switch part points down towards the pedal, and is held on by the plastic nut. It fits in a welded ring on the frame.

The long spring attaches to the 'pull out' plunger and the other end attaches to a hole in the top of the brake pedal.

When you depress the rear brake , it pulls the plunger out and this makes the internal switch close and the rear light goes on.

I appreciate yours may be different but it may be helpful.




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Thanks for your reply, yeah mine is different. The brake switch is the back side of frame and the pedal has no hole for spring to attach.

I have attached some photos but no matter which way I position the linkage it doesn’t work. It actually pushes the spring in when you push the brake on.

where I have put the red arrow. I wonder if that bracket will help in some way?

further investigation is needed.

thanks again NEO


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Thanks Neo 

I think I will get a new one but still don’t know how the linkage works. Might have to improvise a little to attach spring to brake pedal. I have posted on Facebook forum for someone to post any more photos, hopefully someone will send photos without too much abuse🤞
thanks again for your help cheers Graham 

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and this photo shows the little tag poking up just behind the brake pedal


one of the photos shows a close up of the brake side....you can just about make it out.

This gives an indication that the tag has to be uppermost.




Yes, there looks like a small spring attached to that arm, do you have that?

Edited by NE0
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Nice one, you’ve got keen eyesight,

I will have another try in morning.

at least I now know I’ve got the right linkage.

when I dismantled this bike I was too cocky thinking it would be easy to suss everything out but I was wrong.

cheers Graham 

As for the spring I’ve got a collection of them but will look for the original in my drawer 👍

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