I have search all proportioning valve treads on here and got some good info, althought I need a little extra info on the pin that needs to be pulled out while bleeding the brakes and then pushed back in after the bleeding is done.

I replaced my rear brakes shoes , drums, wheel cylinders the other day. I then bleed my brakes so I can get that DAMMM brake light turned off on my dash. I bleed them twice and the light is still on

How far should the pin pull out on the end of the proportion valve? I got a pair of visegrips on it and could only pull out about a quarter inch..does this seem right? or should it pull out more????

 

The reason you pull out the pin is to collapse the metering valve in the front of the proportioning valve when you bleed the front brakes. This lets fluid push right past the metering valve and out to the fronts, instead of having to compress it first, thereby eliminating the risk of trapping air in the proportioning valve. The pin should be held out the entire time the front brakes are bled, and returned once bleeding is complete. I do this with a small pair of nippers, wedged in to hold the pin out. The pin does not pull out very far.

The pin has nothing to do with re-centering the differential valve in the middle of the proportioning valve. That's a common misconception which is erroneously circulated among misinformed individuals. If all you did was install rear wheel cylinders and you did NOT touch any part of the front braking system, then the pin will not affect anything as it only affects the front brakes which are isolated from the rear brakes.

There are two reasons the light comes on: (1) there's an actual pressure difference in between the front and rear braking circuits, or (2) the switch is shorted. If the light was off before you changed out the rear wheel cylinders and now it's on, then chances are there is air in your rear brakes or you have a leaking wheel cylinder.

 

I changed out the front brakes and calipars last year. But before that I noticed that the PO had the brake warning switch unplug'd from the proportioning valve. I pluged it in and the light was on. Thats when I redid my front brakes and still the light was on. So I order'd a new brake warning switch and installed it. Still the light is on. Thats why I replaced my back brakes although they needed it!!!

While I was bleeding my brakes I got all the air out of the lines. I guess I will only bleed the front brakes tomorrow with the pin pulled and see what happens.. I called my local junkyard and they want 5o bucks for a vavle!! thats kinda pricey if I don't need one!!

Thanks FMC 400!!!

 

After you have bled both front and rear brake systems, if the light is still on crack one of the bleeder valves (either front or rear) and SLOWLY press the brake pedal down. If the light goes out stop immeadiately and tighten the bleeder. If the pedal goes all the way to the floor and the light is still on, tighten the screw and repeat on the other (front or rear) half of the system.

 

Mikeoo0o0o... Should I do this while the truck is running or just with the key on the accessory ?

 

check the e-brake pedel it might not be in the up position.

 

The truck doesn't have to be running. The point of this is just to force a drop in pressure in one of the circuits, and try to get the differential valve to move the other direction as you press the pedal.

I'm not sure if the brake warning light is hot in ACCessory, or only hot-in-RUN. I thought it was only hot-in-RUN, in which case you'd need to keep the key in RUN and not in ACC.

 

I dont have the e-brake hooked up yet. The PO took off the e-brake, why? I don't know!! So the e-brake shouldn't be the problem.

I will have the key in RUN and bleed one side and I will let you know what happens.

Thanks everyone

 

The emergency brake doesn't have any effect on the warning light. Unlike modern trucks, dentsides don't have a parking brake warning light. The brake warning light is for brake failure only.

 

Well I pulled the pin and bled just one caliper while had my wife slowly press the brake. Did it 4 times and the light is still on... So then I went and did the other side and what do ya know... the light is still on..

This weekend Im going to buy a loaded master cylinder and new lines going from the cylinder to the valve. If that doesn't help my last option is to replace the porprotioning valve.. And If that doesn't help Im gonna drive it off a darn cliff.. lol

 

if you just did right and left it won't do anything. You have to do front and rear. It doesn't matter whether you do right or left but you MUST do front and rear.

 

The switch itself is a normally open(continuity)spring loaded device.Maybe is has stuck or frozen in the closed position.Remove it from the proportioning valve and check the operation of it.Let us know how it works out for you.

 

I will try that ..I wont beable to until the weekend since I have to go back to work tomorrow.. vacation went too fast!!!

I will keepp u guy updated.