Msd window switch need help

[Jeffie ON JUICE]

Ok guys i finally picked up a msd digital window switch
i have a zex nos system, that has 3 wires
black- ground
white-throttle position sensor, voltage output sensor
red- 12volt arming switch

the msd gives me to options to tie into

gray- normally closed. This wire will remove the ground source at your desired on rpm, and complete the ground circuit at the set off rpm

yellow- normally opened, this wire will provide a ground source at your desired on rpm, and remove the ground at the set off rpm.

Which one do i use gray or yellow?
And what wire do i tie it into ?
I hate elec stuff ;(

[1loudGT]

Jeff I used the yellow wire. I would say tie the yellow wire into the black wire since the yellow will provide the ground.

[Jeffie ON JUICE]

Thats what i was thinking

[Metallicarokerx]

Jeff I used the yellow wire. I would say tie the yellow wire into the black wire since the yellow will provide the ground.

This is what I did.

[titter]

Yup makes the most sense to me, no ground = no power. Add the ground to complete the circuit with the yellow wire.