Kill switch blowing fuses

The last couple of times I've used my kill switch when entering my shop, I noticed the lights went off. Discovered that when I hit the kill switch, I also blow the accessory fuse (15 amps). The only things on the accessory circuit are the headlight and tail/brake light.

The kill switch is a two wire button switch that is connected directly to the coil and grounded to the frame. Thought I'd ask some advice to try and figure out why it's doing this, and what I can do to fix it.

now thats what I call a Kill switch, or maybe overkill switch. Hope you find the short

Take out the fuse, wire a sealed beam headlamp or similar load in its place, start bike, shut it down with your killswitch, and see if lightbulb illuminates and how bright it gets. Also does it stay illuminated while the killswitch stays depressed? If it does, try wiggling your wiring harness around to find the short. If the light flickers or goes out, you found the area. Likely heat has melted two or more wires together that should not touch. Sounds like wires are shorted together and the coil is grounding out through your lighting circuit. Check your killswitch from switch terminal to ground point with an Ohmmeter. Make sure battery is disconnected when using the ohmmeter. Good luck.

Your scooter most likely is not OEM wiring, if the coil feed is on the same circuit as the lights and you apply a direct ground to the positive side of the coil then it would P/O the fuse. Is this a new situation after a mod or something that came around from a change of habit on your part? Always return to the scene of the crime (LOL)

My wiring isn't OEM. Wired it myself in a simple "chopper style" and have had no problems for three years until I installed the button switch. It has its own circuit. It's the 15 amp fuse between the battery and the ignition switch that blows every time I hit the kill switch, thus shutting off the lights. Here is a sketch of my wiring and a pic of the switch I'm using:

Josh,I'm thinking your kill switch should be in series with your R/B ignition wire. To me,that diagram looks like you're grounding out(shorting) your ignition switch instead of cutting power to the coil...

I'm trying to trace the wiring diagram for the kill switch in my SM for the Evo but the diagram seems to have got a lot smaller over the last couple of years

Looks like the kill switch is wired from the positive coil terminal directly to ground and he's using a normally open switch,when he pushes the button to kill the engine which closes the circuit,the juice goes straight to ground and pop goes the fuse killing the engine

I think he'd either have to wire the switch in series(B/R on both sides of switch) or add a relay,but to wire it in series he'd need a normally closed switch rated for the power of the ignition circuit...

I agree with Lucifer, why can't you ground the negative side for the kill switch?

Since it's a grounding switch, it's basically shorting the battery straight to ground. There goes your fuse. Move the kill switch wire to the points side of the coil and you should be golden. It'll draw a lot less current since it's now got the resistance of the coil (3~4 ohms, so a 3~4 amp draw instead of a dead short) in series.

That switch won't work in series, it's a 2 pole normally open switch. Push it to make contact. I know JP sells 'em both 1 terminal and 2. The 1 terminal just switches the single wire to ground. The 2 terminal ones merely connect the two leads. If you put it in series, it'd be a dead-man switch....you'd have to hold the button down to keep the bike running.

I'll try that as I've taken the switch off and it looks good, but I must wait till it gets a bit warmer outside. I can kick it all day when it's cold like this and I'll wear myself out before it starts. Once it gets around 60+ degrees it'll start up a lot easier.

Found this on the www @ club chopper forum...if you want to go with a latching relay and grounding the neg side of coil doesn't work and you can find a spot to hide a relay

look at this link
http://www.oldvolkshome.com/headrelay.pdf

12v to #30and #56
56a and 56b switch back and forth
#S to momentary switch
other side of momentary switch is a ground
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Well fellas, there was no need for a relay - switching the wire to the bottom (point end) of the coil worked. No more blown fuses and everything works fine. (Thanks Sameolddoc!)

Incidently, I had a great day out riding today with a buddy, who just bought a very clean 7 year old Fatboy with only 16,000 miles on it. It has gobs of chrome extras. He stole it for $12,000. Just got home a while ago as the temps are dropping rapidly and rain will begin this evening through tomorrow. At least now, there are more ridable days than not, even though this has been an unusually long cold spell. No global warming for these parts. Next week promises to be in the mid 70s and only one or two rain days and - I have 10 days off for Easter Break starting today. Ya-hoo!

As always, thanks for all the input, boys. I expect some of us may have learned something today - I know I did .

Glad it all worked out for you! (Now to get my hands on another Shovelhead.)

Hope you do - there's nothing quite like 'em. My motor is a stock '77 (1200), with a mild performance Andrews cam and heads rebuilt by Dennis Thurlow.

Mine was the '82 FXRS over there on the left. Bought it with a knock in the bottom end for a good price with full intent to make it a little bigger. Ended up with a 96" S&S kit, S&S Super B with Thunderjet and accel. pump, Leineweber J-2 cam and springs, mild porting on heads and Barnett clutch. Was an awfully fun bike to ride.