Neutral safety switch.

[LostMy65]

Saved for reference...
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Originally Posted by ray_mcavoy

The auto trans neutral safety switch should look like this:
http://www.classicparts.com/1960-72-...ctinfo/53-615/


Both the neutral safety switch and reverse light switch are built into the same housing. So there are 2 pairs of terminals. The two perpendicular terminals (to the left in that pic) are for the reverse lights. And the two parallel terminals (to the right in the pic) are for the NSS.

The NSS has two purple wires and neither one of them is live all the time. One of those wires receives power from the ignition switch "SOL" terminal when the ignition switch is in the "start" position. When the shifter is in park or neutral, the NSS switch contacts are closed and it passes power on to the other purple wire that leads to the starter solenoid.

If your truck is equipped with factory reverse lights, it'll have a couple of green wires (light & dark green) going to the reverse light terminals on the switch.