Lights issue

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Oct 22, 2025 | 04:49 AM

lourias

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6th Gear

Joined: Aug 2025

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Lights issue

I have a strange issue, sometimes after I've been driving at night and I have turned my truck off if I press the brake pedal the dash lights come on, dimly but come on none the less. This doesn't happen every time either. Is this the symptom of a loose ground or something else?

Thanks for you help

77 F250 4x4 351M

Oct 22, 2025 | 06:40 AM

77&79F250

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Joined: Feb 2007

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From: S/W Missouri, Polk county

Sure sounds like you have some sort of wiring issue. The only power going to the cab, (with the truck shut off) is battery to brake switch (under steering column), then to brake lights. If the dash lights come on, when you hit the brake pedal, again there is an wiring issue you need to dig futher into.

And of couse the other items that have constant power (with the truck off) are the cig lighter, dome light (once you open the door), glove box light, headlights and horn. Oh and also the back of the cab "cargo" light (if installed).

Oct 22, 2025 | 10:00 AM

tbear853

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Joined: Feb 2004

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From: The Shenandoah Valley

Quote:

Originally Posted by lourias

I have a strange issue, sometimes after I've been driving at night and I have turned my truck off if I press the brake pedal the dash lights come on, dimly but come on none the less. This doesn't happen every time either. Is this the symptom of a loose ground or something else?

Thanks for you help

77 F250 4x4 351M

Is a new one on me.

I don't think is a ground as the brake lights are grounded at the rear of the truck. The instrument panel has it's own ground too. But, with key off, if you step on the brake, juice will flow to the brake lights from the brake pedal which is somehow bleeding into the instrument lighting. I can't think of a commonality between them ... BUT the brake light wire (Red / Black) does go up through the steering column to the turn signal switch .... and back down to go to the lights as two wires (Yellow / Black to left rear and Green to right rear).... and if an automatic, there is a shift illumination lamp wire (Red/Blue) up there too .... and it could be a pathway to instrument lights as they work together. Maybe pinched, or other issue behind the steering wheel?

That above is "for a fact" correct for my '77. There is a curved grey multi wire connector under the dash where the switch leads plug into the truck, there is a female and a male to each wire, they are secured in the connector with a red "lock strip".

I don't know of your issue, this is just my best guess.

Last edited by tbear853; Oct 22, 2025 at 12:38 PM. Reason: subbing a clearer chart