Brake warning light
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Freshman User
Joined: Jan 2004
Posts: 45
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From: Vancouver Island
Brake warning light
I own an 84 f-250 4X4 diesel....Now the problem... I just put in a new master cylinder,vacuum pump,pads,front calipers, vacuum booster, and rear brake shoes...Opon doing so a rear wheel cylinder blew...OK... no problem replaced both of those..but now the warning light won't go out... Have gone through 2 liters of DOT 3 bleeding and bleeding, and also tried back bleeding...
Still the light is on......But But ...if I push down on the peddal the light is on, but as vacuum pressure builds and the pedal moves down about 3".. the light goes out....( this is the way to reset the differential valve, my manual says ) but as the pedal comes bakc up as it reaches the top the light comes back on
....
So I pulled the electrical plug on the top of the differential valve, think that might shut the warning light off... Nope... with that unplug the same thing as described above happens.....
The brakes seem to work ok.. but are a bit stiff... when the light is out they work great...But I can't figure it out IS there something I am missing O WISE ONES OF THIS FORUM....
Please help I don't want to take the old girl out behind the shed and put her out of her misery...
Still the light is on......But But ...if I push down on the peddal the light is on, but as vacuum pressure builds and the pedal moves down about 3".. the light goes out....( this is the way to reset the differential valve, my manual says ) but as the pedal comes bakc up as it reaches the top the light comes back on
....So I pulled the electrical plug on the top of the differential valve, think that might shut the warning light off... Nope... with that unplug the same thing as described above happens.....
The brakes seem to work ok.. but are a bit stiff... when the light is out they work great...But I can't figure it out IS there something I am missing O WISE ONES OF THIS FORUM....
Please help I don't want to take the old girl out behind the shed and put her out of her misery...
Logistics Pro
Joined: Aug 2003
Posts: 4,701
Likes: 6
I know you are probably sick of bleeding it, but sounds like the proportioning valve is the problem. Bleed it according to the book, but buy or borrow a vaccuum bleeder. They work great. I did a bone dry system on my f250 when I converted to 4x4, and this thing did great, and never had a problem with the valve. Make sure you keep topping off the master cylinder, of more air will get in the valve. Good luck, Ted
New User
Joined: Oct 2003
Posts: 9
Likes: 0
From: NE Ohio
You're close, but need another pair of hands (feet?) to help you finish it off. Have someone push the brake just until the light goes off and <<hold it>> right there. Then open bleeder on the RABS valve so the pressure equalizes inside, close it, release pedal.
Here's what's happening. Imagine a three position spring switch, Left Center Right, resting position should be center. Yours is being pulled to the the L or R position at rest and moves to the the center when you apply pressure. You want to push it to the center position, stop there, equalize the pressure (adjust springs), close the system. Then it will "rest" in the center and move L or R with pressure. Now make the conceptual change from spring and pulled to hydraulic and pushed.
Get hold of a Haynes manual, there is a very good explanation there.
Fred
Here's what's happening. Imagine a three position spring switch, Left Center Right, resting position should be center. Yours is being pulled to the the L or R position at rest and moves to the the center when you apply pressure. You want to push it to the center position, stop there, equalize the pressure (adjust springs), close the system. Then it will "rest" in the center and move L or R with pressure. Now make the conceptual change from spring and pulled to hydraulic and pushed.
Get hold of a Haynes manual, there is a very good explanation there.
Fred
Hotshot
Joined: Oct 2003
Posts: 17,799
Likes: 104
From: Ashland City, TN
i might have to do that too. Mine wont always go on. But sometimes when i press the break it jumps on.
******* i baught the truck from thought that you didn't have to bleed new break lines. haha. i laughed at him.
******* i baught the truck from thought that you didn't have to bleed new break lines. haha. i laughed at him.
