79 dash brake light
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
As stated above, the bulb should come on as the key is turned to START. The ignition switch has a PROVE-OUT terminal to ground out the bulb as the key is turned.
You're saying the bulb will not come ON if you try to start the truck in PARK? Power to this circuit has nothing to do with the neutral safety switch, so it's completely agnostic as to what gear the truck is in. Has your wiring been modified at all?
You're saying the bulb will not come ON if you try to start the truck in PARK? Power to this circuit has nothing to do with the neutral safety switch, so it's completely agnostic as to what gear the truck is in. Has your wiring been modified at all?
.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
I can't tell you what's wrong because I don't know what the previous owner did. Here are some wiring diagrams (1979 at the bottom) if you want to trace through it yourself.
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
1973-1979 Ford Truck Wiring Diagrams & Schematics - FORDification.net
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