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Which Switch

2718 Views 21 Replies 18 Participants Last post by  Louisville Joe
I used to think I was an electrician, but when it comes to understanding the difference between the kill switch by the throttle and the key switch knob, I'm lost.

I've had 3 Harleys now with a combined mileage of over 200k miles and I've never used the kill switch by the throttle. On the Dyna, I just turned the key and the power was off. On 2 Electra Glides, I always used the key knob. When I turn it on, I wait till the engine and security lights go off then I push the start button.

To me, a switch is a switch. A switch in a circuit has to be able to handle the amperage and be the same amperage if in series with other switches. I've heard many of you guys say not to use the key knob but to use the kill switch. How is one switch better than the other for removing power from the engine?

Which leads me to ask why I need 2 switches.

I searched and couldn't find the answer.
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Think this was asked before. Sort of asking who does and does`t use the switch.
I grew up hearing it called the "kill" switch.
A lesser version of a dead mans switch, or "kill cord\tether" you may find on a lot of highly modified machines. Designed that should the rider come outta the seat the power is instantly shut down.
I guess you are supposed to remember to flip it of in the event of an emergency, impending lay down or crash.
I`m on my 3rd bike since 1984. Never used it on any other then once just to see if it worked.
:dunno
Huh. I feel ya. I always thought it was a deterrent for some idiot trying to steal your scoot. If they somehow got the ignition switch turned on, it still wouldn't start if the kill switch was off. I never use it, except when I'm out and about and parked somewhere.
I never use the kill switch when shutting the scooter down. But I will in an emergency.
Maybe I'm a creature of habit or a lil too anal retentive but I've always used my kill switch?
Maybe it's my imagination but the pre-firing of the injectors sounds like it lags if I just keep the kill switch on and use the ignition to be my off/on switch? Thanks guys, now you got me scratching my head!!!
The switches only handle very, very little amperage. They are only controlling a relay which handles the amperage to the device being controlled. I look at it this way. Being in a factory for almost 30 years and doing the machine maintenance, each machine has a stop/start station and a separate emergency stop. In effect, doing the same thing as far as stopping the motor. Not much different here.
The switches only handle very, very little amperage. They are only controlling a relay which handles the amperage to the device being controlled. I look at it this way. Being in a factory for almost 30 years and doing the machine maintenance, each machine has a stop/start station and a separate emergency stop. In effect, doing the same thing as far as stopping the motor. Not much different here.

Hmmm... I was always under the impression that it would damage the ignition systems if not followed in the proper sequence??? Am I wrong in thinking this???
My kill switch is always in the run position. The power goes on and off with the ignition switch. The only time I use the kill switch is if I'm working on the bike and need the power on, but, not the engine.
I caught hell for not using the switch during my rider safety course. I'm a creature of habit so now I just use it
I guess I'm old school. I always use my kill switch before turning off the ignition. I learned on bikes that didn't have a key, only a kill switch. I've also driven older school busses, turning off the ignition would not stop the engine. You had to push in/pull out the kill switch.


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I thought it was a quick way to kill engine with out taking your hands off the bars. Your thumb is right there. Not all bike builders have ignition switch on fuel tank.
Makes absolutely zero difference which switch you use to turn off the motor.

Post Evo days, the ignition is controlled by the Ignition Control Module.
The Ignition Control Module takes a reading from both switches to determine if it should tell the coils to fire. 2 switches do the same thing. The routing of the wires is different, but they both end up at the same place.


Pre Evo days, the 2 switches were wired in series so that both switches had to be "On" for the coil to fire. If either switch was "Off", the ground to the coil was broken, therefore no spark created.
me i think that kill switch is there for if you lay down ur scoot (god forbid u do) that its there to kill the engine so its not screaming while stuck on full throttle. make sense to me any way. all my dirt scoot,s were this way. if u don't practice using it , then when that day comes u might not remember to kill it. (god forbid u don't ever lay down ur scoot,s)
As mentioned either switch is fine and it won't damage the bike no matter which way you do it.

That said on my Dyna I stopped using the kill switch because I would then forget to turn off the ignition switch which would cause the battery to run down.

The problem is that people who should know better keep the myths alive. When I took posession of my '14 Street Glide the guy that gave me the walk through said if I didn't use the kill switch first it would cause the engine light to come on for a while. I immediately thought "BS" and proved he was wrong by testing his theory.
I thought it was a quick way to kill engine with out taking your hands off the bars. Your thumb is right there. Not all bike builders have ignition switch on fuel tank.
My ignition is on the left side of the motor. I use the kill switch pretty much every time. Only forgot to turn off my ignition once. Dead battery cured me of that.
In times past I used the kill switch if I was parking on an incline or for whatever reason I would put the transmission in gear and leave it. It was a reminder that there was something unusual that I needed to take care of before starting. Now I use it in almost every case. Gee thanks. Now that I'm getting old and my memory is going you give me something else to think about, lol.
Another thing I do is leave it in gear when parked. Unless it's running of course. I've never really understood putting it in neutral when parking it. I don't go to neutral at lights either.
As I understand it, the kill switch is there because of some government rule that says it has to be there. It is supposed to be en emergency cutoff in case you drop the bike and can't reach the main ignition switch. I think the efi bikes have an internal switch in case the bike is dumped....someone jump in here and verify or refute that one.
As for the kill switch, I have heard the tales that damage will befall your system if you don't use it. I have never used it on any of my bikes over the years and so far, no damage.
Engine will shut off if bike lays down (Don't ask me how I know this for sure) I also use kill switch it is just handy for me. FLHTK-2013 FLHTCUTG-2014
As I understand it, the kill switch is there because of some government rule that says it has to be there. It is supposed to be en emergency cutoff in case you drop the bike and can't reach the main ignition switch. I think the efi bikes have an internal switch in case the bike is dumped....someone jump in here and verify or refute that one.
As for the kill switch, I have heard the tales that damage will befall your system if you don't use it. I have never used it on any of my bikes over the years and so far, no damage.
I had an '09 1200 Sporty with a "lean angle indicator" somewhere on the bike. Found that out by reading the owner's manual after I had a tip over and it wouldn't immediately restart. Turned IGN off then on and fired up OK. Haven't read anything in my '11 or '13 owner's manuals about a lean angle indicator. Unless there is such a gizmo on a bike then the bike has the same risk as a car with an electric fuel pump--if you have an accident and the IGN is on the fuel pump will keep pumping. That could be bad with a ruptured fuel line.
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