Brakes keep seizing

[Dean2]

The plunger is certianly not working, when i compare the plunger length to pics on the internet of the replacement part it is far shorter with little play, I am going to go NAPA and see if i can get one and compare, buy one if necessary and try that. However is it possible that a faulty brake swtich would cause the brakes to lock up?

The switch is not faulty. Your problem is your brake pedal is NO LONGER travelling far enough to engage it. Worked fine with the old MC and Booster. Still works I bet if you push it by hand. Take the defective parts back to where ever you go them from and get them to replace it or refund your money.

 

[Brad88888]

The plunger is certianly not working, when i compare the plunger length to pics on the internet of the replacement part it is far shorter with little play, I am going to go NAPA and see if i can get one and compare, buy one if necessary and try that. However is it possible that a faulty brake swtich would cause the brakes to lock up?

just replaced the switch, still have the same problem.

 

[diymirage]

The plunger is certianly not working, when i compare the plunger length to pics on the internet of the replacement part it is far shorter with little play, I am going to go NAPA and see if i can get one and compare, buy one if necessary and try that. However is it possible that a faulty brake swtich would cause the brakes to lock up?

my guess is the plunger on your new master cylinder is not shorter, it is stuck
think about it, you press the brake, and the linkage pushed the plunger down sending pressure to the brakes

you let off the pedal, the linkage backs off, the plunger backs off and the fluid backs out of the lines and back into the master cylinder reservoir (of course not all fluid, im oversimplifying it)

now, lets say the plunger is out of spec, its 3 thousands of an inch thicker then it should be, and the passage is also out of spec, but it is 2 thousands narrower

now, you have a push fit

meaning you can press the pedal, and the plunger moves forward, but when you let off the pedal there isnt enough pressure to release the plunger

how would that look?

visually, the plunger would appear shorter, and mechanically the brakes would lock up


did you try to back the plunger out by hand?
or let it sit for a while and when you feel the brakes are not locked up, take a look at the plunger and see if it doesnt look longer

 

[Dean2]

just replaced the switch, still have the same problem.

As in the brake pedal still doesn't reach the switch? Parts Cannon in rapid fire mode is NOT going to solve your problem.

 

[GTyankee]

P0572 Cruise Control/Brake Switch A Circuit Low

The proper operation of the brake switch is integral in the operation of your cruise control system. Given the fact that, one of many ways to disable or turn off cruise control is to depress the brake pedal, you will want to take care of this. Especially if you use cruise control in your day-to-day commuting. The letter designation in this case -- "A" -- may be referring to a specific wire, connector, harness, etc. To determine which one this code refers to, you will need to check out the appropriate manufacturer-specific service manual. If you are having a hard time finding what you need, it's always a good idea to look for a wiring diagram for the cruise control system. These diagrams, a lot of time, can provide you with valuable information (sometimes location, specifications, wire colors, etc.) The P0572 Cruise Control/Brake Switch A Circuit Low and related codes (P0571 and P0573) are set when the ECM (engine control module) detects a malfunction within the cruise control/brake switch "A" circuit. In this case it means there is a detected low voltage condition within the circuit.

Read more at: https://www.obd-codes.com/p0572
Copyright OBD-Codes.com



Causes for this P0572 cruise control code may include:
Cruise control/Brake switch defective
Wiring issue (e.g. pinched on brake pedal, chafed, etc.)
ECM (engine control module) issue (i.e. internal short, open, etc.) Debris/dirt mechanically hindering brake switch operation
Brake switch not adjusted properly
Brake switch out of it's mount

read more :

P0572 Cruise Control/Brake Switch A Circuit Low

How to quickly diagnose, repair, and causes of a P0572 diagnostic code which indicates a detected low voltage condition within the cruise control brake switch A circuit.

www.obd-codes.com

My guess would have been different.
I was thinking about the proportioning valve

 

[Hagar1]

If the piston in the Master Cylinder is not coming back far enough to clear the compensating port, there will be residual pressure in the brakes system. As the brakes heat up, the fluid heats up and expands a bit and puts MORE pressure on the brake.
Get a helper to press the brake pedal while you are watching the fluid in the master cylinder, you should see a little "spurt" of fluid coming up or at least some movement in the fluid. Make sure you wear eye protection because getting brake fluid in the eyes hurts like Hxxl!
If the fluid is not showing any indication of "moving" there is a strong possibility that the master cylinder piston isn't coming back far enough. You could get a good idea of the length required for the pushrod between the master and the booster. Put a straight edge across the back end of the master cyl, with a caliper or other accurate depth guage measure the distance from the recess in the bottom of the piston to the underside of your straight edge. Then with the pushrod fully seated in the booster, measure the amount that the pushrod extends from the booster. Then it is just simple math to see if the rod is the proper length.

 

[04fxdwgi]

Anyone think the ABS module may be wigging out?

 

[fireflymedic]

I had a old dodge truck that did this. It was the rod that went from brake pedal to master cylinder had no gap or play. It touched even when pedal was,all the way up. So vibrations from driving would slowly beld up pressure. Adjusted so had quarter inch gap . Wala no more problems.

 

[Hagar1]

Anyone think the ABS module may be wigging out

I replaced my front calipers a couple of weeks ago, they were old and were not retracting good. I then realized that I had a sinking gas peedle, so i checked for leaks on all brakes however there were none and I looked very heard pumping thee brakes many of times. I then figured it has to be the master cylinder, which i just replaced. Once the master cylinder was installled I bled the lines and thought everythng was good. When I did a test drive the brakes became more and more seized as i used them for all four brakes. Does anyone know what can be happening in this case?

An

I replaced my front calipers a couple of weeks ago, they were old and were not retracting good. I then realized that I had a sinking gas peedle, so i checked for leaks on all brakes however there were none and I looked very heard pumping thee brakes many of times. I then figured it has to be the master cylinder, which i just replaced. Once the master cylinder was installled I bled the lines and thought everythng was good. When I did a test drive the brakes became more and more seized as i used them for all four brakes. Does anyone know what can be happening in this case?

Any progress? Any updates?

 

[62Blazer]

just replaced the switch, still have the same problem.

Isn't this plunger and switch you are talking about simply for turning the brake lights on and off? If I'm thinking of the same thing that part has absolutely nothing to do with the brakes at the wheels engaging......
As stated above it doesn't sound like that switch has an issue, but the pedal is not moving correctly or far enough.
Just because a part is new doesn't mean it's good! Dorman has a pretty poor reputation in the automotive world. There are many good mechanics that refuse to use Dorman products unless that is the only option.

 

[Tominator223]

What’s the yr & mileage. A sinking pedal could be air in the system. A bad booster usually hiss’s in the cab. If a push rod is on the edge of the cylinder & not centered that will engage brakes. And a bad vinyl line will also engage brakes

 

[Jd3443]

I had a 2003 Ram 1500 that the abs module started going bad and the pedal actually got “softer” the longer you had your foot on the pedal. Had a mechanic replace the abs module and now it always has a nice firm brake pedal. What year and model truck are we dealing with here from the OP?

 

[Marshall]

ABS pump problem? I have had a sinking pedal with old fluid and air in the system
I would have to look on mine, but after a lock up, could you just pull the pin on the brake peddle to pull the rod back more to see if they release.

 

[Sherman Bird]

Isn't this plunger and switch you are talking about simply for turning the brake lights on and off? If I'm thinking of the same thing that part has absolutely nothing to do with the brakes at the wheels engaging......
As stated above it doesn't sound like that switch has an issue, but the pedal is not moving correctly or far enough.
Just because a part is new doesn't mean it's good! Dorman has a pretty poor reputation in the automotive world. There are many good mechanics that refuse to use Dorman products unless that is the only option.

I had a 2003 Ram 1500 that the abs module started going bad and the pedal actually got “softer” the longer you had your foot on the pedal. Had a mechanic replace the abs module and now it always has a nice firm brake pedal. What year and model truck are we dealing with here from the OP?

Are you sure the "module" was the problem, not the "HCU" or Hydraulic control unit? I'm just trying to clarify!

 

[Sherman Bird]

Anyone think the ABS module may be wigging out?

I've never seen an ABS module with a wig on!

 

[Hagar1]

What’s the yr & mileage. A sinking pedal could be air in the system. A bad booster usually hiss’s in the cab. If a push rod is on the edge of the cylinder & not centered that will engage brakes. And a bad vinyl line will also engage brakes

A sinking pedal "could" also be an indication of a primary cup in the master cylinder that is leaking, The fluid creeps past it and goes back into the master cylinder reservoir.

 

[BadHemi2014]

I realize this is an older thread with no follow up from OP, but I had a similar issue in my Beetle so thought I would leave this info for future users.
In my case the master cylinder was replaced. (Tbh I don't remember original symptoms,I think a sinking pedal, but irrelevant here.)
After driving the car for a bit, I realized that the brakes would not release. It was evident that all 4 wheels were affected as they were all extremely hot.
After dithering around and having a couple people try to diagnose, I replaced the master cylinder again.
Problem solved.
I can only assume the first replacement was faulty. The first one was not done by me, but the 2nd one was.

I also want to add that brake switches on these trucks are goofy. I had to replace mine, it was cracked. The new one I had to add a couple layers of grip tape to the end of the plunger for it to make contact with the arm of the pedal. Hey it works.
Recall that the switch has nothing to do with the mechanical action of the brakes, it just completes a circuit to turn the brake lamps on.

 

[JambaJoe]

I recently emailed this thread to the service writer at my local Ram dealer. It resulted in the brakes finally working properly although somehow now the electric side of the ABS is now bad but no parts available. Here's the background.
I went to Firestone to get a new set of tires. My brake pedal had excessive travel for about a year and I noticed that they advertised doing brake work. I asked them if they did master cylinders since I suspected mine was bad. They said they did do master cylinders as well as the other brake components. I told them to go ahead and do the tires then check out the brakes. They later sent me pics via email showing me the pads and rotors needed replacing as well as the brake fluid. They said they would have to replace those before they could determine if the master cylinder was in fact bad. I said go ahead and replace the rotors and pads ($1100). They then notified me that the master cylinder and booster were bad. They replaced them ($1200). I picked up the truck and drove it home (3 miles). By the time I got home, almost no pedal travel and brakes overheated and dragging. I went back the next morning and left it. They supposedly re-bled the brakes and said all was good. I picked it up and drove it home. Once again, overheated brakes and dragging and this time the check engine light came on (ABS code). I called them and they said they had no idea why it was doing that but I could bring it up there the next week when their "master mechanic" came in. Apparently he is in their shop twice a month. I took it up there and left it. The next day they told me the ABS was bad and I would have to take it to the dealer. I went to the dealer and dropped it off. The next day the dealer called and said the brake fluid was contaminated and the hydraulic side of the ABS was bad because of it. They replaced it ($2000). They test drove it the next day and it still was dragging on all 4 wheels. They told me they were in touch with corporate to determine what might be wrong. A week later they called and said the calipers and hoses would have to be replaced. At this point, I wasn't sure what to do. I was fast approaching the value of the truck. I told them to go ahead and replace them ($2200). 3 days later I called them and they said the brakes were still dragging. By then I had come across this thread and emailed it to them. A day later they called and said my truck was ready and the brakes worked great but the ABS light was staying on. Since that part doesn't exist anymore, they couldn't replace it. I told them if the brakes work I don't care about the ABS light. I was done spending money. I'm into the brakes for $6500 as it is. Other than excessive pedal travel, there was nothing wrong with the ABS until someone worked on it. When I asked the service writer at the dealer about how they fixed it, he said the tech said something about adjusting the plunger rod which leads me to believe the problem started at Firestone. I apologize for the long discourse but maybe it will save someone unnecessary expense in the future.

 

[Ritchie_Rich]

But I just installed a new master cylinder. Possible it is defective? I did buy it from amazon.

Amazon. There ya go.

 

[Hagar1]

I replaced my front calipers a couple of weeks ago, they were old and were not retracting good. I then realized that I had a sinking gas peedle, so i checked for leaks on all brakes however there were none and I looked very heard pumping thee brakes many of times. I then figured it has to be the master cylinder, which i just replaced. Once the master cylinder was installled I bled the lines and thought everythng was good. When I did a test drive the brakes became more and more seized as i used them for all four brakes. Does anyone know what can be happening in this case?

Check to make sure that the master cylinder piston is "coming back" far enough to clear the compensating port. If it doesn't, you will have a problem such as you describe. This is not an "uncommon" thing to happen when a master cylinder has been changed. The length of the push rod between the master and the booster might need adjustment.