brake warning lamp
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New User
Joined: Feb 2004
Posts: 3
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From: Houston
brake warning lamp
Three weeks ago I flushed my old brake fluid and replaced with fresh DOT 3. Now, my brake warning light refuses to stay out. There are no leaks at the wheel cylinders and I'm not losing any fluid from the master cylinder. I have reset the light a number of times, but after driving half a mile or so, the light comes on again. Any suggestions?
Senior User
Joined: Dec 2006
Posts: 281
Likes: 0
From: Woodstock, Portland, OR
i had sort of the same problem with my 68 f-250. no booster or anything. i replaced the m. cylinder becasue i was loosing fluid from it, and my light is still on. this is what i think the problem is.
if your pedal soft or mushy, you probably have a leak somewhere in the system, or air bubbles.
your Pressure differential valve assembly might be a little worn or even stuck. either that or when the lines get to the PDV assembly, you might have a leak. i think you can get new switches for it, but i would just go the easy route and get a new assembly and put it in, but first i would check the wiring for shorts, etc. you will have to drain your system and re fill and re bleed if you have to replace it, but yeah. if theres nothing wrong with the lines or the mechanicals of it, its probably a short in the wiring.
if familiarize your self with the PDV by staring at diagrams of it for hours on end, youll find out hat the problem is. always works for me.
if your pedal soft or mushy, you probably have a leak somewhere in the system, or air bubbles.
your Pressure differential valve assembly might be a little worn or even stuck. either that or when the lines get to the PDV assembly, you might have a leak. i think you can get new switches for it, but i would just go the easy route and get a new assembly and put it in, but first i would check the wiring for shorts, etc. you will have to drain your system and re fill and re bleed if you have to replace it, but yeah. if theres nothing wrong with the lines or the mechanicals of it, its probably a short in the wiring.
if familiarize your self with the PDV by staring at diagrams of it for hours on end, youll find out hat the problem is. always works for me.
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Post Fiend
Joined: Dec 2003
Posts: 6,658
Likes: 4
From: "Islander"
When you bleed the brakes front and rear the side your not bleeding will have a higher brake line pressure that will push the plunger off center causing your failure light to go on.
Slowly just crack open the bleeder while appling pedal pressure, you will have to try front and rear to get the plunger to center, light will go out.
A PITA to center with an old sticking plunger.
Slowly just crack open the bleeder while appling pedal pressure, you will have to try front and rear to get the plunger to center, light will go out.
A PITA to center with an old sticking plunger.
