Lighting problem

Strange problem on my 2002 wr426, found neither head or tail lamp were working on dipped or main beam, checked brake lamp and that works fine but only when other lights are switched off. Brake lamp doesn't work when dipped or main beam selected.

I've tried disconnecting head lamp plus tail lamp in turn, checking for earthing of live wires and also the switch, but found nothing wrong.

Anyone out there with any clues or just got to resort to miners lamp?!

I'm sure you checked, but does the switch have continuity on both settings? Did you check the switch w/o the wires attached (ie - directly on the terminal), or did you do it through a connector block? I'd look at the wiring to the switch if the switch is good on both hi and low with no wires attached.

How is the voltage distributed on this bike? Is it factory wiring or aftermarket?

Thanks for your ideas

I checked the continuity through the connecting block, but also took the switch apart but could see nothing amiss, but i'll have another look.

The wiring is pretty much as it left the factory but found a diode connected in the loom, not sure on what circuit or what it's for. the manual i have for the bike gives a very poor diagram of the bikes curcuits and without the brake light illustrated.


Since it is factory, I would bet on there being a relay to provide the +12 VDC to the lighting circuit. That's where I would look next. Make sure you have 12 volts to and a good ground from it. That will energize the coil when the light switch is on. Next, make sure the 12 volts is on the output side of the relay. When the switch is on, it will energize the coil, closing the contacts and providing 12V to the lighting circuit. If you have 12V to the relay but the contacts aren't closing, you won't light the lights. I'd check the wiring to and from the relay. There will most likely be 4 wires to the relay. The reason the brake light may work when the other lights are off is that it may be a separate circuit.

Kinda guessing here w/o a manual. If you could scan your diagram and email it to me, I could prolly help more. Good luck with it.

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