Electrical Woes

My front & rear lights only work IF the connection to the hydraulic/elctrical switch attached to the rear brake cyclinder is disconnected !

I obviously have some sort of a short in the electrical system here. I know 0 about electrics. About time I learned I guess..anybody got any ideas or had this problem before ?


Do you have a buddy with an ohmmeter, and knows how to use it? It has to be either a short/corroded wire or the switch has shorted itself out.

Does the front switch work OK?


Follow the wire that you disconnected back to the wiring harness. Wherever that might be. Once there you will need to use an Ohm Meter with a beeper for a continuity check. Attach either lead to the post that runs to the switch on the rear master cylinder. Then with the other lead touch each post and listen for a beep. If you get a beep the display on the meter should read 000.2 or so. That means that these two wires are shorted together. Then you will need to follow the other wire to see where it goes. Along the way you will need to look at the complete wire to see if it has rubbed together somewhere. If you don’t find anything there check the other side of the wiring harness. If nothing there then follow the wires from your rear light all the way out. Check for bare wires or melted wires. Do the same on the front. If you check the wires for the lights it will say that they are shorted as the bulb element acts as a heat dissipater, which is where the light comes from. Try these things and see what you find. If you don’t have an ohmmeter just check all wiring from each light as I described earlier. And maybe you know this already and I am talking out my ass. But this is what I do for a living so hopefully I can help.


another thing is to concider if the switch i a NO or NC switch. Normally open or normally closed. you can find that out using an ohn meter again. Connect to each post of the switch and use the beep function on the meter. then push the switch open and closed. if you get no beeps then check resistance on eachopen and closed. One should be 000.2 or so if not you may have a bad switch and that could cause it. just another thing to check i guess

The insulation on the wires coming out of the rear brake light switch on my bike have have worn throught to the bare metal more than once. It was an easy fix to reinsulate them with heat shrink tubing. I have since rerouted and lengthened the wires so they won't wear through anymore. The heat from the exhaust pipe seems to weaken the insulation.

I have the Baja Designs kit on my bike so the ground has been "floated". (Whereas the normal ground is the engine/frame.) The symptoms I noticed were no brake light when activating the rear brake and reduced battery charging efficiency.

Guys, you are life savers. It all makes sense,... sort of (I'm a marketeer !!). I even have an Ohm meter but one that dates back from when my dad was an apprentice in the Royal Navy. It works, again sort of, doesnt beep but IS an anitique so it has SOME value !

Anyhoo i'll be rolling my sleeves up tomorrow. I feel the problem is around the leads going to the brake switch thing as they are in a terrible state.

Thanks again.

Is this a new install or did it work O.K. before?

good luck. hopefully this will help you. i am going to go home and check mine.

The rear brake light never worked and when I bought it the lights never worked. I took it back to the dealer and he fixed the lights for free but the brake light never worked...until...that is yesterday...

I ripped the harness off of the bike (the biut leading to the rear brake switch anway. It was melted through and was shorting against the frame.

I re-routed the new cable (220 Volt light switch cable) on the top part of the frame, away from the exhaust and replaced the connectors. I'm hpoping the insulator on the cable will help dissipatre the heat more than stock.

Anyway I'm well happy as I feel (more) comfortable riding and not being rear-ended by some idiot on four wheels..... wait... sorry... there's another thread about that somewhere....

Anyhow...thanks all for the tips.

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