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Brake warning light on and off when pressing pedal?

flamesoldier

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The brake warning light stays illuminated but when pressing in brake it goes off. I pumped the pedal quick and hard several times to balance the adjuster internally if that was problem and no dice. I drove it and slammed on brakes and rear right leaves a quick skid mark photo enclosed on quick driveway skid so you can see. What is my problem going on here? Is my proportioning valve shot, do i need to rebleed brakes, or is master cylinder going out?

IMG_9980.jpeg
 
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heminut

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First thing I would do is pull the left rear wheel and drum and check the self adjusting mechanism. It may be stuck and not adjusting the shoes out properly. That would explain why you only have one side locking up.
 

flamesoldier

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Would that cause the light situation too?
First thing I would do is pull the left rear wheel and drum and check the self adjusting mechanism. It may be stuck and not adjusting the shoes out properly. That would explain why you only have one side locking up.
 

Xcudame

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I hope that the front brakes locked up (skid marks of rubber on both sides) prior to the rear locking up! The front MUST brake before the rear or you're going to go around and around in circles!! Regarding the light, it sounds like the switch has failed and needs replacement. Personally I think the light is totally useless, when the brakes are bad, you'll know instantly because the pedal will go all the way to the floor! Been there, done that at 70 mph!
 

flamesoldier

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I hope that the front brakes locked up (skid marks of rubber on both sides) prior to the rear locking up! The front MUST brake before the rear or you're going to go around and around in circles!! Regarding the light, it sounds like the switch has failed and needs replacement. Personally I think the light is totally useless, when the brakes are bad, you'll know instantly because the pedal will go all the way to the floor! Been there, done that at 70 mph!
Car brakes even and smooth and also doesnt spin around when panick braking test but will be going through system to check everything including adjusting rear drums. I bought a nos switch so gonna see if that resolves that. Just got the car so gonan give it a once over
 

Challenger RTA

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Above info is good. The light being on could below low on fluid. It needs a little pressure to keep the light out. I would Bleed the brakes again. If it has a reset valve make sure it is out. If it happens again it might be a master cylinder going bad. Bleeding into the brake booster. You have a booster?
 

flamesoldier

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Above info is good. The light being on could below low on fluid. It needs a little pressure to keep the light out. I would Bleed the brakes again. If it has a reset valve make sure it is out. If it happens again it might be a master cylinder going bad. Bleeding into the brake booster. You have a booster?
I have power booster front disc rear drum with the iron style kelsey hayes proportioning valve
 

Challenger RTA

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I should say it can be the proportioning valve going bad. that's what mine did. I took it apart and rebuilt it. All is good.
 

flamesoldier

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I should say it can be the proportioning valve going bad. that's what mine did. I took it apart and rebuilt it. All is good.
Yea was thinking that. If everything checks out will go that route, i was told musclecar research has the reseal kits, i also wander if i could get a new brass style and it will fit lines
 

Challenger RTA

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I don't what to say yes, but I don't see why not on the brass valve. Someone else may have done that.
 
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Challenger RTA

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From what I understand disc drum. There is a residual valve that keeps 5-7 psi in the rear brakes. That being said the sw could be tested with shop air. and a test light or meter. Put 10 psi or more to the sw. If the light goes out it's good. the problem is else where. The brake psi can be as high as 600psi.
 

Xcudame

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Just make sure your brakes work well! We don't you or Challenger in "flames"! Brakes are #1, Steering #2 for safety. Chrysler always has (and still has) the best brakes. When it came out, the Dodge Viper was the quickest car from zero to 100 mph to zero!
 

Ricks72Chlgr440

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I hope that the front brakes locked up (skid marks of rubber on both sides) prior to the rear locking up! The front MUST brake before the rear or you're going to go around and around in circles!! Regarding the light, it sounds like the switch has failed and needs replacement. Personally I think the light is totally useless, when the brakes are bad, you'll know instantly because the pedal will go all the way to the floor! Been there, done that at 70 mph!
I bought a new one from Dr Diff and it was bad right out of the box.
 

Ricks72Chlgr440

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My question is did you have the iron type and it changing the brass type bolt right up?
I had a brass one already installed. Dr Diff told me what I had was for drum/drum and I needed to change it to the disc/drum, which I did. It bolted up easily but the one I took off was not an iron type.
 

sixpactogo

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Yea was thinking that. If everything checks out will go that route, i was told musclecar research has the reseal kits, i also wander if i could get a new brass style and it will fit lines
IMO, I would stick with the original valve and get the parts to rebuild it if necessary. I have had a couple of the brass units from Inline tube fail from new so they don't have a real good track record. I think all you need is the pressure switch and yours will function as new.
 

Xcudame

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Or you can do what I did on my 70 Challenger about twenty years ago and replace the original valve with a tee and install a regulator on the rear brake line. the dumb brake light on the dash is useless. Who needs a red light when the brake panel goes to the floor! When the brakes fail, you're pumping like a mad man to make "air" brakes work!!
 
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