wiring issue
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From: Parma ohio
wiring issue
hello all I'm new here and I have a wiring issue with my 68 f100 does any know what the one purple wire that runs from the ignition switch to the break differential valve is for because it burned up on me and now I cannot start the truck at all now anything is very much appreciated on how to find this problem thanks
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From: Parma ohio
would that be the purple wire that come off the back of the ignition switch?
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From: Parma ohio
that's exactly what it is I finally got it running tonight thanks for the help very appreciated thank you
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The terminal on the side of the switch that the Purple wire connects to is known as the "Prove Out" or "Proof Out" of a switch. It grounds through the body of the switch to the dash in the START position only and when grounded turns on the Brake Warning lamp.
However, this circuit in no way should effect the engine running. Completely separate circuit (usually anyway) and so could not kill the engine unless something else had shorted to it first. Which might explain the melted wire. In most cases, the failure comes at the pressure differential switch and the light stays on all the time. Annoying enough that most people just disconnect it.
Are you saying that once you removed the wire from the switch, you could start the engine again? That's strange. Looks like I'll have to go back and re-familiarize myself with the wiring diagrams!
But hey, as long as it's running! Congrats on the quick fix.
Paul
However, this circuit in no way should effect the engine running. Completely separate circuit (usually anyway) and so could not kill the engine unless something else had shorted to it first. Which might explain the melted wire. In most cases, the failure comes at the pressure differential switch and the light stays on all the time. Annoying enough that most people just disconnect it.
Are you saying that once you removed the wire from the switch, you could start the engine again? That's strange. Looks like I'll have to go back and re-familiarize myself with the wiring diagrams!
But hey, as long as it's running! Congrats on the quick fix.
Paul
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From: Parma ohio
The terminal on the side of the switch that the Purple wire connects to is known as the "Prove Out" or "Proof Out" of a switch. It grounds through the body of the switch to the dash in the START position only and when grounded turns on the Brake Warning lamp.
However, this circuit in no way should effect the engine running. Completely separate circuit (usually anyway) and so could not kill the engine unless something else had shorted to it first. Which might explain the melted wire. In most cases, the failure comes at the pressure differential switch and the light stays on all the time. Annoying enough that most people just disconnect it.
Are you saying that once you removed the wire from the switch, you could start the engine again? That's strange. Looks like I'll have to go back and re-familiarize myself with the wiring diagrams!
But hey, as long as it's running! Congrats on the quick fix.
Paul
However, this circuit in no way should effect the engine running. Completely separate circuit (usually anyway) and so could not kill the engine unless something else had shorted to it first. Which might explain the melted wire. In most cases, the failure comes at the pressure differential switch and the light stays on all the time. Annoying enough that most people just disconnect it.
Are you saying that once you removed the wire from the switch, you could start the engine again? That's strange. Looks like I'll have to go back and re-familiarize myself with the wiring diagrams!
But hey, as long as it's running! Congrats on the quick fix.
Paul
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