Kill switch question - purple wire

[RedBed]

So I read that the purple wire coming from the steering column is supposed to be a good place to put a kill switch. Even verified the purple wire with my mechanic.

So I clipped it and added a "switch".

I then tested it with the connection broken - and the truck STARTED.

WTH did I do wrong?

[RedBed]

Or is it this purple wire (fatter)

[ray_mcavoy]

The purple wire in your first pic looks like the one going to the turn signal switch. With that circuit open you simply won't have any turn signals.

The heavier gauge purple wire in your second photo is the one you would want to use for a "kill switch" that would prevent the starter from engaging. But just to be sure, follow that wire (along with the yellow wire beside it) and you should be able to follow them to where they plug into the neutral safety switch on the column.

[RedBed]

Not sure if I can see where it goes into the column, as it is part of that taped up bundle. Does it go through the firewall to the starter?

[ray_mcavoy]

If you follow the wires after they branch out of the taped up bundle, they should lead to the plug on the neutral safety switch. The neutral safety switch is located inside the cab on the steering column just before it passes through the firewall.

The yellow wire runs from the "start" terminal on the ignition switch to the neutral safety switch. Then the purple wire runs from the neutral safety switch, to the bulkhead connector (in behind the fuse box). The bulkhead connector is where the majority of the wiring passes through the firewall. From there, the purple wire continues on to the starter solenoid.

The neutral safety switch is closed when the transmission is in "park" or "neutral" and should be open in all other gears, preventing the engine from being started while the trans is in gear. By temporarily unplugging the yellow & purple wires from the neutral safety switch, it will open the circuit (preventing the engine from starting) and verify that you have correctly identified the wires without having to cut one of them.