Dual brake switch

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Oct 4, 2025 | 05:10 PM

w951wxj

Thread Starter

Mountain Pass

Joined: May 2003

Posts: 236

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From: Milwaukee USA

Dual brake switch

1973 f100 base LB. I have an orphan purple wire from my ignition switch. According to wire schematics I've seen this appears to be wire 977 that I think goes to the dual brake warming switch on the proportion valve and then I think the out bound wire from the warning switch goes to the dash idiot light. Please let me know if that is not a correct interpretation. Wiring is not my special super powers but I'm working on it.

Thanks

Last edited by w951wxj; Oct 4, 2025 at 05:11 PM.

Oct 4, 2025 | 11:28 PM

tbear853

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Joined: Feb 2004

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From: The Shenandoah Valley

Looks like it. Ignore the blue / red, it was for a separate issue. I added the purple / white.

Last edited by tbear853; Oct 5, 2025 at 10:29 AM.

Oct 5, 2025 | 08:19 AM

Rubiranch

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Joined: Jun 2004

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From: South Central Utah

I unplugged the electrical connecter on the proportioning valve because the red warning light on the dash was always and it was very annoying.

The red warning light doesn't annoy me anymore.

Oct 5, 2025 | 10:26 AM

tbear853

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Joined: Feb 2004

Posts: 10,866

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From: The Shenandoah Valley

Quote:

Originally Posted by Rubiranch

I unplugged the electrical connecter on the proportioning valve because the red warning light on the dash was always ......

Was it always on from when you got the truck? You ever try resetting it? Mine only ever comes on when I put the key in the switch and turn to run, just before turning to start.