How To Wire A Master Cutoff Switch?

Mustanger · 02-10-2005, 12:48 AM

Can anyone tell explain to me step by step how to install a Master Cutoff Switch. I relocated my battery to the trunk, but the rules state that I must install a Master Cutoff Switch that when turned off, will kill the power and shut the car off. I have no clue how to wire that. Help please...

Jeff Chambers · 02-10-2005, 07:07 AM

(+) from battery to one post of switch
(+) from other (NO) post of switch to solenoid
(-) from battery directly to GOOD chassis ground
12V hot from alternator to same (NO) post of switch

~The Jester~ · 02-10-2005, 07:38 AM

I thought you had to put the alt on the battery side of the switch? If not, won't it keep the car running even when you throw the switch? We just had this discussion in another thread, and if I'm wrong I gotta go correct that other post! LOL

Jeff Chambers · 02-10-2005, 12:55 PM

It needs to go on the post that goes dead when the switch is thrown to the off position. If connected to the battery side of the switch, the alternator will continue to see 12V and run on, continuing to fire the ignition.

red82gt · 02-10-2005, 01:14 PM

Quote:

Originally Posted by Jeff Chambers

It needs to go on the post that goes dead when the switch is thrown to the off position. If connected to the battery side of the switch, the alternator will continue to see 12V and run on, continuing to fire the ignition.

I second that. If the alternator hot wire went to the battery side, it would keep feeding power to the battery, you just wouldn't be able to start the car.

~The Jester~ · 02-10-2005, 04:54 PM

OK, which alt wire are we talking about? I'm running my "charging" wire (Typically +14v) all the way to the back of the car (according to mad electric) for other reasons. Are we talking about the same wire? Or are you guys running the field wire back there?

Mad Electric tech

red82gt · 02-11-2005, 12:50 AM

Wait, I screwed up. The one from the B+ terminal on the alternator has to go to the same side as the + battery terminal, otherwise the car would keep running off the alternator.
My bad, shoulda known, after all mines hooked up that way. I've been away from home working for the last 5 weeks (mineral exploration camp in northern Canada)-starting to lose my mind.

02-10-2005, 12:48 AM	#1
Mustanger Dot Racing Join Date: Jan 2005 Location: newark Posts: 16	How To Wire A Master Cutoff Switch? Can anyone tell explain to me step by step how to install a Master Cutoff Switch. I relocated my battery to the trunk, but the rules state that I must install a Master Cutoff Switch that when turned off, will kill the power and shut the car off. I have no clue how to wire that. Help please...

02-10-2005, 07:07 AM	#2
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: How To Wire A Master Cutoff Switch? (+) from battery to one post of switch (+) from other (NO) post of switch to solenoid (-) from battery directly to GOOD chassis ground 12V hot from alternator to same (NO) post of switch __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

02-10-2005, 07:38 AM	#3
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Re: How To Wire A Master Cutoff Switch? I thought you had to put the alt on the battery side of the switch? If not, won't it keep the car running even when you throw the switch? We just had this discussion in another thread, and if I'm wrong I gotta go correct that other post! LOL __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

02-10-2005, 12:55 PM	#4
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: How To Wire A Master Cutoff Switch? It needs to go on the post that goes dead when the switch is thrown to the off position. If connected to the battery side of the switch, the alternator will continue to see 12V and run on, continuing to fire the ignition. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

02-10-2005, 04:54 PM	#6
~The Jester~ Rat Killer Join Date: Aug 2002 Location: Cold ass Ohio Posts: 1,143	Re: How To Wire A Master Cutoff Switch? OK, which alt wire are we talking about? I'm running my "charging" wire (Typically +14v) all the way to the back of the car (according to mad electric) for other reasons. Are we talking about the same wire? Or are you guys running the field wire back there? Mad Electric tech __________________ d-Con Racing "Nothing fancy, just 347 inches of RAT POISON!" MICE need not apply.....

02-11-2005, 12:50 AM	#7
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	Re: How To Wire A Master Cutoff Switch? Wait, I screwed up. The one from the B+ terminal on the alternator has to go to the same side as the + battery terminal, otherwise the car would keep running off the alternator. My bad, shoulda known, after all mines hooked up that way. I've been away from home working for the last 5 weeks (mineral exploration camp in northern Canada)-starting to lose my mind. __________________ 393W: AFR 205's, hydraulic roller, TKO600.

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