How to wire a Battery cutoff switch

rd

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Jan 12, 2000
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How do you wire a battery cutoff switch to make the NHRA happy, and to protect or properly shut down the alternator?

Ie, if I get the fancy switch with two poles, which wire goes to the second set of contacts, the alt output wire or the alt field control wire.

It seems to me, that interrupting the field wire is what the normal key shutdown does, that stops alt output. I read that you can damage the alternator if you do not shut it off correctly.

I think I am making this too hard, but ????

Thanks
 
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Mephisto

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May 10, 2004
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http://www.timskelton.com/lightning/race_prep/weight/battery_relocate.htm

The cutoff switch must be connected to the POSITIVE side of the electrical system and must stop all electrical functions. The off position must be clearly indicated with the word OFF. If the switch is push/pull type, push must be the action of shutting off the electrical system, pull to turn on. Any rods of cables used to activate the switch must be minimum 1/8 inch diameter. Plastic or keyed switches prohibited.
You cannot simply hook your positive battery cable to the cut off switch. The truck will continue to run if you disconnect the battery. You must also tap into the power to the PCM relay to be cut off as well, from the same switch, so the truck will stop running when the switch is used.
1. Run a # 1 cable from the ON side of the switch up to the original battery cable that hooks to the solenoid on the fire wall.

2. Unhook the alternator cable from the solenoid on the fire wall and hook to a #2 wire and ran it back to the battery side of the switch.

3. Take a #1 wire and run from the battery positive side to the battery side of the switch same side as the alternator wire.

4. Run a #2 wire from the negative side of the battery to a good ground on the frame (make sure you clean the paint etc. away before connecting the ground to the frame!)

5. Up front I just cleaned a spot on the frame of the truck and I connected the ground wire to the frame. Keep in mind I didn't cut ANY factory wires because I might want to put it back to stock again one day.
batt_relo_wiring.jpg
 

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