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Old 06-02-2011, 11:58 AM   #1
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Default kill switch not killing the car.

well if my car is off and i turn the switch off, the car loses power.
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
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Old 06-02-2011, 12:02 PM   #2
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need to interrupt the + side of the battery by rule and you need to run the alternator output through it as well to kill the car when its running. Otherwise, the alt will keep the car powered
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Old 06-02-2011, 12:16 PM   #3
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what Fireball just said is correct... what is happening is the Alternator is keeping the car running with the battery disconnected.

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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Old 06-02-2011, 12:44 PM   #4
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my pos. side looks like this
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Old 06-02-2011, 12:58 PM   #5
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run the alt wire to the batt or the batt side of the switch easy fix.
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Old 06-02-2011, 01:36 PM   #6
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yeah swtich needs to be on Positive side of the battery. Batter and alternator need to be on 1 side of the switch and starter and fuse pannel feed need to be on other side of the swtich
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Old 06-02-2011, 02:39 PM   #7
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I noticed that if I disconnect the pos. Of the battery it dies.
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Old 06-02-2011, 03:10 PM   #8
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The wire running from the ALT needs to go strait to the battery, and then the wire from the battery needs to run to the on/off switch, then up to the starter solenoid/starter, and the fuse box....
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Old 06-02-2011, 05:04 PM   #9
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Quote:
Originally Posted by JL ws-6 View Post
The wire running from the ALT needs to go strait to the battery, and then the wire from the battery needs to run to the on/off switch, then up to the starter solenoid/starter, and the fuse box....
it can be ran from the alt to the battery side of switch as well
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Old 06-02-2011, 08:28 PM   #10
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Yeah you can do it that way. I just run it strait to the battery, personal preferance.

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.
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Old 06-02-2011, 10:31 PM   #11
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Alternator wire direct to battery will do the trick, but I am pretty sure it is not legal per NHRA rules.

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.
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Old 06-02-2011, 10:48 PM   #12
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I don't know about that... I never had a tech problem with it set up that way. We ran the wire from the ALT right to the battery, then the + battery cable went thru the switch, which then had on the other side of it, the power cable to the hotwire kit for the fuel pump, and a 0 ga welding cable that ran up to a bulkhead fitting in the hvac delete plate.. wire from there went to the starter, 2nd went over to the fuse box.

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.
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Old 06-02-2011, 11:18 PM   #13
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My car was wired the same way when I first got it. The alt would keep it running. So I redid it like everyone here is saying and it works great.
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