what is this light?

76Kroh · Post by **76Kroh** » Tue Mar 03, 2015 1:30 am

screen shot windows 7

What is this light for that is above the parking brake release? Only comes on when starting the truck. Is there supposed to be a lense over it?

Pat Crash · Post by **Pat Crash** » Tue Mar 03, 2015 1:58 am

Brake Pressure Differential Valve. The light stays on if there is an issue.

I had to have mine rebuilt as it was difficult to get the light to go out after working on the brakes.

More info here: http://www.fordification.com/forum/view ... hp?t=11614

76Kroh · Post by **76Kroh** » Tue Mar 03, 2015 8:02 am

Pat Crash wrote:Brake Pressure Differential Valve. The light stays on if there is an issue.

I had to have mine rebuilt as it was difficult to get the light to go out after working on the brakes.

More info here: http://www.fordification.com/forum/view ... hp?t=11614

OK good to know. Thx!

67 StylesLide · Post by **67 StylesLide** » Fri Jun 26, 2015 6:16 pm

So where is the switch?
I have seen it off but mostly mine stays on. Maybe from having disc brake conversion?

HIO Silver · Post by **HIO Silver** » Fri Jun 26, 2015 8:40 pm

The light is to indicate a fault with the brake system and that the piston in the prop valve/distribution valve has defaulted to either the rear or the front brakes. The switch is threaded into the valve's body... it has a pin which usually sits in a detent of the piston. If the pistons moves too far to one side the pin rides up the piston's machined surface and completes the circuit to illuminate the light.

bluef250 · Post by **bluef250** » Fri Jun 26, 2015 10:04 pm

The light is grounded by the switch on the pressure differential valve and also grounded to ignition switch on start. Otherwise the light should go on while in start and if one side of the brakes fail (when the truck was built).

66f250cs · Post by **66f250cs** » Sat Jul 11, 2015 12:53 pm

I will add to other posts; The chrome bezel with red translucent disc is missing but the shell is there. To replace, press the spring loaded assy from the back side towards rear of truck. Doing so will push the shell forward. Grab the front of the shell and twist. Install replacement bezel.

oafboy182 · Post by **oafboy182** » Mon Jul 20, 2015 4:51 pm

I was just about to ask about this until I saw this post. The light in my truck is blue and on all the time. How do I reset it?

oafboy182 · Post by **oafboy182** » Mon Jul 20, 2015 4:57 pm

Just saw the link in an above post. Hopefully I can figure it out.

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