Brake dummy light on dash.
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
If the light wont go off with the method of centering the switch, you don't have a parking brake operated warning light, and the light goes off after the porportioning valve is unpluged...
The only logical possibility would be a stuck or malfunctioning porportioning valve.
The only way to fix that problem is to replace the porportioning valve.
If it is stuck, and you have a future problem with a wheel cylinder leaking or brake line failing, the potential for total brake failure and not being able to stop your vehicle is higher, because of the lack of warning, and the way the porportioning valve works.
Nobody can say for anyone to ignore the light, cause of liability issues, and you must get the light fixed, cause it's illegal in all 50 states to drive any vehicle that has any brake component or warning device impaired or malfunctioning.
And also of note, your insurance company may not cover you in any accident you have, Your fault or the other drivers, cause you knew the light isn't working properly, or that you knew there was a problem with the brake system, and drove the vehicle anyway.
Hope this helps.
The only logical possibility would be a stuck or malfunctioning porportioning valve.
The only way to fix that problem is to replace the porportioning valve.
If it is stuck, and you have a future problem with a wheel cylinder leaking or brake line failing, the potential for total brake failure and not being able to stop your vehicle is higher, because of the lack of warning, and the way the porportioning valve works.
Nobody can say for anyone to ignore the light, cause of liability issues, and you must get the light fixed, cause it's illegal in all 50 states to drive any vehicle that has any brake component or warning device impaired or malfunctioning.
And also of note, your insurance company may not cover you in any accident you have, Your fault or the other drivers, cause you knew the light isn't working properly, or that you knew there was a problem with the brake system, and drove the vehicle anyway.
Hope this helps.
Posting Guru
Joined: Jun 2004
Posts: 1,635
Likes: 0
From: Niceville, FL.
Actually, you can remove (unscrew) the brake warning switch from the proportioning valve body an test it. With switch plunger pushed in the brake warning light should be "off", with plunger out the light should be "on". It is spring loaded in the out or light "on" position.
Posting Guru
Joined: Jun 2004
Posts: 1,635
Likes: 0
From: Niceville, FL.
howler, that's true for the rear brake stoplights. The brake warning light in the instrument panel is a totally different circuit that works off a switch in the differential proportioning valve, a switch terminal in the ignition switch (supplies ground in "start" position only for a lamp test) and the parking brake switch (if so equipped).
New User
Joined: Oct 2006
Posts: 21
Likes: 0
According to chilton's, the way to correct the porblem is to turn the key foward to ac and have someone depress the brake and you have someone else to loosen the brake line (bleeding)at the master cyclinder. either of the two lines. The book says try one and then the other. this will allow the valve to center itself. Whenit is centered the lite will go out. this is in the 1980-1986 chiltons book.
Cargo Master
Joined: Apr 2003
Posts: 2,058
Likes: 424
From: Too close to Houston
Originally Posted by gtripledip
According to chilton's, the way to correct the porblem is to turn the key foward to ac and have someone depress the brake and you have someone else to loosen the brake line (bleeding)at the master cyclinder. either of the two lines. The book says try one and then the other. this will allow the valve to center itself. Whenit is centered the lite will go out. this is in the 1980-1986 chiltons book.
Elder User
Joined: Oct 2006
Posts: 552
Likes: 0
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New User
Joined: Oct 2006
Posts: 21
Likes: 0
please read the tread.
No don't start over. Turn the key to accessory, the brake light will come on, have someone depress the brake pedal while you slow loosen one the the brake lines at the master cyl. When the light goes out the piston is centered. you shouldn't lose much fluid.
Posting Guru
Joined: Nov 2004
Posts: 1,137
Likes: 2
From: Asheville, NC
If it was the back brakes that were leaking fluid, then loosen the connection for the front brakes at the master cylinder while an assistant is pressing the pedal for you. Have him/her tell you when the light goes out. You wont lose much fluid, either. Check the master cylinder fluid level after you are finished, ALSO, tighten the connection you losened before your assistant lets up on the pedal. This way, you wont draw any air into the system. This approach works. I did it on my '83.
I also suggest rags or towels around and under the master cylinder to catch any spraying fluid. The fluid can ruin paint.
I just love it when there is an unexplained electrical "problem" how many guys think its an automatic SHORT in the wiring. Hee hee hee.... If the light wont go off, you simply unplug the electrical connector at the switch on the differential valve below the master cylinder... down near the frame.
My truck has very good brakes. Still has the OEM drum brakes in the back, with new wheel cylinders, and new disc pads and callipers on the front. 189K and still truckin!!!
I also suggest rags or towels around and under the master cylinder to catch any spraying fluid. The fluid can ruin paint.
I just love it when there is an unexplained electrical "problem" how many guys think its an automatic SHORT in the wiring. Hee hee hee.... If the light wont go off, you simply unplug the electrical connector at the switch on the differential valve below the master cylinder... down near the frame.
My truck has very good brakes. Still has the OEM drum brakes in the back, with new wheel cylinders, and new disc pads and callipers on the front. 189K and still truckin!!!
Posting Guru
Joined: Sep 2003
Posts: 1,192
Likes: 1
From: lino lakes, mn
the e-brake switch if equiped is easy to check just pull up on the brake pedal but you don't have one you have a stuck p-valve switch another way to reset it is turn the ignition swith to the run position have a helper hold pressure on the brake pedal then you crack the lines loose on the master cylinder tighten it up as soon as the light goes out or try cracking the bleeders loose if you look in the manual it says to block the pin on the p-valve when the brakes are being bled