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Pedal travels, lose braking power, Parking light comes on

sled_dog

sled_dog

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Alright, a few times now my Parking brake light has come on, I lose braking power(not all but a good bit) and my pedal gets pretty darn soft and travels down not to the floor but not far from. I've never checked my back brakes so I'm thinking its certainly time to do so. No obvious fluid leaks, and the master cylinder is slightly low, but when I say slightly I mean just slightly. Anyway have a thought? I never use my Parking brake(cable is snapped) so I can't see why the light would be coming on.
 
Sounds like your master is toast.

Had the *exact* same symptoms in mine before. I noticed when it did this I could usually "pump up" the brakes with a few pedal applies, but that did nothing more than make sure I could get myself home. :)

If you don't have a parking brake and the master decides to fail, going to have an interesting time stopping.
 
just a little, but back on topic. Could it be a booster problem? My master cylinder went bad and I never had that happened. It just puked all the fluid out between the master & the booster. My dads dually, lost braking power one day and it was the vacuum pump(diesel) gone bad, keeping the booster from functioning. He had the same problem, no pedal and no braking.
 
Arrrr matey! Heave too and drop anchor .

But if you dont want to throw out an anchor every time you want to stop. Replace the master cylinder. It'll only get worse. One day when you really need it, the pedal will just go to the floor and you will say OH SH**!
 
If you lose fluid, (or if it leaks through the seals internally which is what mine was doing) the brake light will come on if the proportioning valve and the light circuit are working correctly.

Only booster I've seen fail (standard vacuum) the pedal was rock hard all the time, and harder than heck to slow the vehicle down.

I spent hours trying to bleed that master cylinder before I just accepted it as being slightly spongy. Took a few months before it finally "gave up". Typical result of bleeding a used master cylinder.
 
The booster on our 94 Suburban went bad the pedal was really hard to push and it made a leaking air sound. Since you said you have plenty of fluid I'd lean towards grabbin the flare nut wrenches and replace that master cylinder. I think I'd still pull off them rear drums and take a look back there just in case one of your slave cylinders isn't doin it's job.
 
yeah if it was the booster pedal would be hard. With the cam I have in my motor it doesn't idle perfectly(tbi + no custom chip) so I have hard pedal and steering at idle. Guess its my master cylinder, I forgot about that prop valve switch setting off the light. It only happens a little but like you guys said, only going to get worse.
 
If I am not mistaken, the tension from the e-brake system is required in order for your self-adjustors(drum brakes) to function. You might try adjusting your rear brake shoes and see if that makes a difference. I also believe that tension from the e-brake system keeps the e-brake pedal in the off position, it could be creeping down, tripping the light switch.
 
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