Derbi headlight hell

First let me start with I’ve spent the last 6 month trying to research this / find out on my own with no success. Started with a super dim headlight when I got the bike.. also someone had rigged up a tomos dash. I’m trying to bypass the two dash lights but now I cannot get my running light or headlight to come on. Brake light works, just no running light or headlight. After deleting the two dash lights I’m left with one blue and one brown. I grounded all the yellow and green. I’m sure this is obvious to some of the veterans on here. Please help!



Re: Derbi headlight hell

Maybe this will help :

Wiring Diagram

Re: Derbi headlight hell


Re: Derbi headlight hell

blue and brown, brown rns power back to the taillight when the lights are switched on, it also runs the speedo backlight, blue is running the high beam indicator light and also high beam. also the stoplight switches from the brake levers are blue, but those r not in the pic

get one of these test lights - clip it to a ground and poke the probe in the wires to see which have power. once you find a light wire that's got power - you connect that to the your light, and the other side to ground and you're gtg. simple.

Re: Derbi headlight hell

holy hell, nevermind me - that wiring diagram is spot on and really easy, you can see the splits, it's dead easy to track those wires!

the little tester is still a good call, theyre cheap and make wiring lights super simple. any autoparts store will have em under $10, probably under $5

Re: Derbi headlight hell

I don’t have a dash or dash lights anymore.. is there a way to bypass them? Something needs to happen with the blue and brown wire.. idk I’m gonna fiddle some more tonight. Sorry this is going way over my head Thanks bois

Re: Derbi headlight hell

You have too many grounded wires .

ONLY the yellow / green gets grounded from the headlight .

The yellow / white and the blue go to the switch ...

Brown from the switch to tail ...

No dash lights = disconnect the block that the brown goes into .

And , the ground should be to the frame proper . Or , run a dedicated ground wire from the bucket to the motor .

That should give you a start . (edited)

Re: Derbi headlight hell

Aight.. now my running light is working.. still no headlight. The second blue wire is what I’m lost over. Grounded the yellow and green from the headlight to a tab on the forks.. even scuffed it up nice n fresh. Cracked open the switch.. looks kind of roasted tbh. I feel like the second blue wire shouldn’t matter.. on the wiring chart it leads to a dash light. Will the light not come on if the ground is bad? Half way there.. may god, and this forum have mercy on my soul.


Re: Derbi headlight hell

A good ground is essential as it completes the circuit . It's why I suggested a dedicated ground wire to the motor .

I can't see the contacts in the switch , but it's likely the switch just needs a good cleaning .

Have you tested the headlight bulb to insure that it is good ? Both high and low beams .

The 2nd blue can be removed or taped .

Re: Derbi headlight hell

I’ll double check the bulb.. starting to think it’s the switch. I’ll go through it and make sure it’s clean tonight. No matter how good my ground was last night the light would not come on. I appreciate the help!

Re: Derbi headlight hell

It was the ground inside the bulb socket.. pulled it out to clean the contacts and the little brass tab fell on the floor. Must have been cracked but somehow it was still there? Idfk anywho I’m back in business!


Re: Derbi headlight hell

Good deal . ;)

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account