Can you explain this further? If the bulb only has one wire running un-interrupted to it, isn't it off? It's not on at all is it?
Trying to understand .
Dan

 

Good question, Dan. I'm guessing that sometimes there can be a high-resistance ground that can sometimes occur, even when the ground wire circuit is open (switch off), so that a little juice passes through the lamp. In the case with the X2, it's all plastic and rubber connections from the lamps to the bike frame so I don't see where any stray juice can get to ground, except through the switch if it wasn't completely opening the circuit. If the circuit isn't completed in any way, how can the lamp use any juice? But that's all just guesses, part of which is based on some funky house wiring I've ran into in the past.

 

I've never heard of put a switch on the ground to kill the headlight. I would think putting a switch on the hot wire going from the fuse block to the headlight would get the result you would be looking for. You would be opening the circuit from the primary power source therefore not allow any voltage through to power the light.

 

I believe 'theoretically' it doesn't matter if you put it on the - or +. As long as you completely open the circuit, the power can't pass. The bulb can't burn any juice if it can't run in AND out. Just like your battery -- disconnect one side or the other and the power doesn't flow. The negative is good because the bulb has three wires going to it: low beam, high beam, ground. With the ground you can install a simple single pole single throw (SPST) switch (on/off) on one wire thereby taking care of the job. I and others around here put switches on the ground and haven't heard of anything bad yet. Works great for me on the TrailTech X2.

 

I just took a quick look of the 2009 wiring diagram that's in the stickies.
If the earlier bikes are wired the same way, I wouldn't put a switch (or a relay) on the ground wire going to the bulb.

If you open that connection the Hi-bean indicator light in the dash will provide the ground path. Meaning, the headlight bulb will glow faintly and the hi-bean indicator will be always on (as long as ignition is on).

Correct place for a switch to turn off the headlight is on the positive wire going into to the hi/lo handlebar switch.

--
Mikko

 

You are correct sir!!! My hi-beam indicator comes on when my switch on the ground wire is in the "off" position. I was wondering if I goofed on my connections (as a previous boss advised: "Always have a few beers before starting any electrical wiring project - a full six pack is best." I actually didn't initially mind the indicator on as I thought it would remind me when the headlight is off, but you can't see it very well in daylight and at night no headlights are plain obvious .

Time for a six pack and a solder gun

 

Just be sure to flip the headlight back on if you see a cop, in a lot of states that could result in a fix it ticket. In my case, I'd risk an inspection.

Law: So, where's the evaporative emission system?

Me: Ummm, in a cardboard box in my garage, sir...

 

Yeah, the bulb has three connections, ground, high beam, and low beam. If you cut the ground, any voltage on either of the two hot leads will find it's way to ground through the bulb filament and the bulb will glow a bit. If the voltages on the hot leads were equal, the bulb would not glow, but because of differences in the length of wires and where things connect, this is very unlikely. I also speak from experience here -- I tried the switched ground lead idea many years ago and learned the hard way.

You COULD use a double pole switch in the hot leads, but even the OEM headlight switches on bikes tend to fail over a relatively short period of time. Relay contacts are designed for high current and are typically more reliable because the relays are sealed and out of the weather.

 

I got into this on my 96' TW200. I thought a simple ground wire switch would work. WRONG. I still had dim lights. I ended up stripping the entire wiring harness and running a new hot to the ignition switch, then hot side switch. I was wanting a complete blackout switch. I had to seperate the lighting circuit from the ignition circuit otherwise the blackout switch would also kill power to the ignition relay. Still, when I turn off the bike the lights stay on until I turn off the new switch and they want come back on until the ignition key is turned??????
I scratched my head on that project for a while!
I've studied the KLX wiring diagram and still haven't got a good game plan. I just don't want to strip that harness too. I've alsoo heard that without the lights the battery could be overcharged. SO FAR my TW is fine but I'd like to know if that's true before doing it to the KLX.

 

I'll see if I can find it later, but for now: there is a thread here that shows a circuit that keeps the headlight LO off at start-up until you hit HIGH beam. Then the lights work as normal. But the bike needs to shut off again to reset the circuit. So you can't kill the lights anytime you want. I have an aftermarket switch for a KLR650 that has an off position but I need a dead '09 left control with the harness intact to be able to wire it in (I want to be able to save my stock control/harness in case I need it again)