Master Cut Off with Denso Alternator

[padam]

I have a single pole master cut off switch installed now. Problem is that the alternator keeps the engine running when the switch is cut.

This also seemed to kill my Denso alternator while I was testing it.

So Im installing a 2 pole switch and I want to get it right the first time.

I have 3 wires coming out of the Alternator. I’m using Andy F’s pigtail.

I have the heavy charging wire, I know I don’t want to cut that one.

IIRC the other wires, 1 is 12v from the run switch, and the other is 12v from the battery. Which of these do I want to cut off with the switch?

 

[33 IMP]

I can't help with your dilemma, im no electrician.
All i know is that I had to use a moroso alternator shutdown relay, cause I have a one wire alternator and a single pole remote switch, that I was unwilling to change. (Relay is part#74107, cost more than a new two pole switch!)
Your two pole shutoff should solve the problem I had, I'm sure someone here can help you out.

 

[dvw]

You can connect the light duty 12v ign on trigger wire to the off side of the switch. One issue is now the field will be hot with the cut off switch in the on position. You can wire the the ign trigger circuit thru a relay. Relay terminal location; Battery + to term 30. Alt trigger circuit to term 87. Ign key on circuit to term 85. Ground to term 86.
Doug

 

[padam]

You can connect the light duty 12v ign on trigger wire to the off side of the switch. One issue is now the field will be hot with the cut off switch in the on position. You can wire the the ign trigger circuit thru a relay. Relay terminal location; Battery + to term 30. Alt trigger circuit to term 87. Ign key on circuit to term 85. Ground to term 86.
Doug

Thanks Doug I will give this a try.

 

[snakeoil24]

You need a diode to stop the run on

 

[gkent]

Is this for racing - to stop the drag from the alternator, or is it as an anti-theft device?

 

[dvw]

You may need a diode. Only if the engine won't shut off with the key. With the toggle switch and relay system, the toggle switch will definitely turn it off w/o using a diode. None of mine have ever needed it. Easy to do. It's in the MSD instructions.
Doug

 

[33 IMP]

Is this for racing - to stop the drag from the alternator, or is it as an anti-theft device?

This is for his racecar. Nhra requires a switch at the back of the car that will shut off the engine, if the battery is moved to the trunk. The problem is the alternator keeps the engine running.

 

[padam]

You may need a diode. Only if the engine won't shut off with the key. With the toggle switch and relay system, the toggle switch will definitely turn it off w/o using a diode. None of mine have ever needed it. Easy to do. It's in the MSD instructions.
Doug

This is for his racecar. Nhra requires a switch at the back off the car that will shut off the engine, if the battery is moved to the trunk. The problem is the alternator keeps the engine running.

Yep, race car wiring, using a toggle switch.
There is not much left of the factory wiring.

 

[padam]

You can connect the light duty 12v ign on trigger wire to the off side of the switch. One issue is now the field will be hot with the cut off switch in the on position. You can wire the the ign trigger circuit thru a relay. Relay terminal location; Battery + to term 30. Alt trigger circuit to term 87. Ign key on circuit to term 85. Ground to term 86.
Doug

This did the trick Doug!

Thanks for the awesome advice.

 

[dvw]

Glad I could help.
Doug

 

[padam]

Nice to see in line at the track.