kill switch not killing the car.
if my car is on and i turn the switch off the car keeps running.
i have the switch on the negitive side of the battery. it goes battery to switch and then from switch to chassie.
how do i need to wire up the kill switch
you need to connect the alternator output wire directly to the battery, on the battery side of the switch.
that way, if the switch is opened, both the battery and the alternator is disconnected.
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But, it absolutely has to be run back to behind the switch. And, the lead powering fuse box, also needs to go to the starter, so it's not being run off the ALT without passing thru the cutoff switch.
Tip: If you have a hotwire setup powering your fuel pump, and the battery is in the back as it probably is (and should be with a cutoff switch), run the power lead for the hotwire off the cutoff switch too. Less wire running up to the front of the car, less voltage loss to the pump, and now when ya kill the power on the switch, you 100% kill the power to the fuel pump... the car WILL shut off for sure now.. and if there's ever an engine bay fuel related fire, it's a good way to make sure that the pump is off and not feeding the fire.
The purpose of the kill switch is to cut off power at the rear of the car and if you have a charging wire ran from the battery to the alternator then this defeats the purpose of the kill switch. There are kill switches manufactured specifically for this purpose and is what should be used so the charging wire is shut off as well at the same time.
So, technicially, the power was coming from the battery, alt hooked up to the battery itself. Hit the switch, and the car instantly died... nothing at all had power, fuel pressure instantly fell to 0, etc.
I'm sure that a relay could have been put in the line, so that when the switch was off the relay would cut the ALT power to the battery.. but I didn't see any reason to make it more complicated.
I will try to look this up in the NHRA book at home when I have a moment, see if it clarify's anything. The one thing that the tech inspectors at lebannon valley, island dragway, cecil county cragway, atco and englishtown all wanted to see, was if the switch killed the car. When it killed the car when it was running, that was all they really cared about. I get that having the wire off the battery up to the ALT leaves a hot wire in the engine bay.. but I can not see a way of not having that be the case, unless you put a relay in the back that would open up when the switch was cut, so the wire running up to the ALT wouldn't have power to it past the trunk wiring. Again.. that seems like a good way to over complicate it, and would just be one more relay/electircal part that could be a problem.







