Ok so I've been having these issues with my brakes, all 4 wheels, just suddenly closing up. I've had the service ride control message for sometime and it never seemed to effect anything. Recently I got the reduced engine power message a lot. It seemed to only do it when it was raining out, but I'd just pull over turn it off and it would go away & I'd be fine. Well the other day I was driving down the road running about 65 & I got the dreaded Stability Service message pop up in my DIC and as soon as it happened it felt like everything bogged down. At first I thought it was the tranny b/c it felt like I wasn't getting out of 1st gear but then I realized my brakes were locked up. So I turned it off, waited about 20 minutes, turned it on & everything was fine. Well later that day on my way home, same problem, had to wait about 30 minutes this time. Well now it seems to be a constant problem. It keeps locking up. I took it to the dealership and all they did was pull a code for the throttle body position sensor and for the auto level ride compressor. So after reading up on it I replaced the throttle body connector since it seems most of what I've read on here pointed to that and I knew the compressor was shot already so I didn't tackle that project yet. But low & behold I have the same problem!!! My brakes just keep locking up. I'm going to pull the ABS fuse & get it to a different dealership but man, I'm just baffled at what could be causing it. Now, I'm no mechanic, but it doesn't seem like the compressor being shot should be making my brakes lock up on me. Sorry for the long post but I wanted to be detailed about issues leading up to it. Anyone ever have these issues happen to them or know what would make it happen? Frustrated is not the word I'm feeling.:hmm:
Crazy brake issues
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try turning the traction control system off and see if it helps on the brakes if yes then you have a wheel sensor failing cause if the system thinks a wheel is slipping it will cut back on the throttle since it electric and no the compressor being bad does NOT affect the other systems
the button for the stablatrac has a car with lines behind it if you want to give it a try and see if it helps before you start pulling fuses.
the button for the stablatrac has a car with lines behind it if you want to give it a try and see if it helps before you start pulling fuses.
Thanks The Cadillac Man but I thought about that & tried it when I was sitting on the shoulder. It didn't do anything but stay the same. 
Thanks for confirming that the compressor wouldn't make the brakes lock up! After I posted yesterday I got to looking & saw that both bags in the bag are gone. One has a hole & the rubber on the other isn't in the best condition. So I know why the compressor is shot now! haha Just annoys me that the dealership was ready to sell me a $800 job to replace a compressor that wouldn't be able to pump anything up anyway!
Thanks for confirming that the compressor wouldn't make the brakes lock up! After I posted yesterday I got to looking & saw that both bags in the bag are gone. One has a hole & the rubber on the other isn't in the best condition. So I know why the compressor is shot now! haha Just annoys me that the dealership was ready to sell me a $800 job to replace a compressor that wouldn't be able to pump anything up anyway!i suggest pulling the fuse until you can check the wheel speed sensors cause that is what it sounds like to me making the system go nuts and apply both the brakes and kill the throttle while you are driving. p.s. the speed sensors are built into the wheel hubs and go nuts as they age with wear.
Well I pulled the ABS fuse in hopes it would create a temporary fix long enough to get it to the dealership but didn't work. Pulled the fuse & it still stays locked up. I'm starting to think it is mechanical instead of electrical. Maybe the master cylinder or hydraulic system? I'm just stumped. Crazy thing is, I drove it for about 5 miles and got up to 40 MPH no problems or traffic at all to work, then after work got about 2 miles down the road in traffic and it locked up. I'm thinking maybe the traffic causing me to use my brakes more & heating up the calipers is some way contributing to the issue. I'm at the point where I'm going to bleed the brake system & send off the fluid to be tested to see if it's been contaminated. Anybody got any ideas or light bulbs going off?
It sounds like you are only experiencing this problem when the vehicle gets hot, correct? As you know heat causes things to expand so you could have any of a number of things cause what you are describing. First thing I would check is that you do not have the master cylinder over filled as this would not allow for the natural expansion in the brake system when it gets warmed up. Although quality brake fluid should not expand until temperatures reach around 500 degrees, if someone put a lower grade brake fluid in your vehicle, this could also cause this. One unlikely, but possible cause is that you may have a brake line too close to a heat source (exhaust pipe) which could certainly cause over expansion. If none of these seem to be the problem, I would lastly guess that you have air in the brake system (air expands faster and at a lower temp then brake fluid) and in this case you should drain the entire brake system and refill it with a QUALITY brake fluid. This is just my assessment from what you have posted, if you agree that heat seems to be cause of your problem then you should explore the options I have listed, if heat doesn't seem to be accurate, then by all means, disregard.
i agree with mike since pulling the abs fuse didn't help matters none try bleeding the system cause if there is air in the system it will cause this.
Thanks guys! I'm going to try and bleed the lines today. I think I remember reading a post some time back where a guy had some of the same symptoms and had to loosen the 2 bolts on the master cylinder right by the firewall to get it to kick loose. I think he had contaminated fluid which I'm hoping that's not my issue b/c I can't even get my head around how expensive a fix the entire brake system would be. I'll keep you updated & thanks again for the help!
So I have an update. I was going to bleed it out myself but wanted to get it done sooner than I knew I'd be able to get around to it so I took it to a shop near my office. I get there, give the guy my symptoms & tell him I think it's mechanical & not electrical. I had already popped the hood to kind of go over what had been done to just eliminate any confusion. So as I'm showing him the connector I say I feel like it could be the master cylinder and I open the cap to it, and as soon as I opened it up I knew what my problem was going to be. The rubber on the cap was swollen & stuck to the tank. BOOM! The guy & I look at each other & kinda both just say contaminated fluid. So he flushed the system, put on a new master cylinder, check the calipers, and brake lines. He got it rolling great again but told me depending on how long the fluid had been in there & how far it got, it might happen again. He showed me the fluid they flushed out & it looks like maybe power steering fluid. I have no idea how it got in there unless the shop I took it to for the inspection did it just to try & get some business. So, does anyone have any idea how expensive or what the best way to go about replacing the parts that could fail b/c of this mishap. I'm guessing maybe the rotors? I dunno, never had this problem before. Any input anyone?
The brake fluid is only inside of the master cylinder, lines and calipers. As far as replacing parts, that should not be necessary unless the fluid in there before was corrosive (eating away at the rubber). You mentioned that the master cylinder cap was stuck, not destroyed, so it sounds more like it just got sticky. Worst case scenario is you would have to remove and clean out each caliper and thoroughly flush and clean the lines, but new parts should not be needed.
mike i know this may sound a bit odd but i have seen some people put power steering fluid in the brake master cylinder also my dad used tranny fluid in the power steering pump in a emergency cause a hose had ruptured although the power steering pump did make a whining noise after that (and it never stopped the whine) even after he replaced the hose and put fresh power steering fluid in the pump so yes the wrong fluid can do damage.p.s it was in a car not in my truck.
I have no doubt that the wrong fluid can cause damage and be corrosive, but it is really hard to advise someone to start replacing parts when they don't even know what kind of fluid they just removed. I would think that since the master cylinder has already been replaced, the other two possible failures I can think of are if the fluid became sticky, the brake calipers would not retract and cause the pads to wear out at an accelerated rate or if it was corrosive it could cause leaks at the seals in the brake calipers at which point fluid would start leaking and the brake pedal would start feeling really soft. Neither of these possibilities would inspire me to outright replace anything else unless I saw these symptoms. Then again, I drive in LA traffic everyday and if I had a brake failure in an Escalade going over 60mph, whoever I hit will not be driving home, at least not in their car.
that is a really good point and i know what you mean about the risk of hitting someone i had a close call my self and i was glad i had good brakes cause if i didn't the old lady who decided to pull out in front of me and stop wouldn't have been walking picture a escalade doing 55-60 mph and then having to come to a dead stop only 6 feet away from the car with a older 2500 gmc pick-up with a trailer behind me nearly hitting me and yes it scared the shit out of me and i'd say the same for the old lady although i had stuff under my seat that i was cleaning out for a half hour thanks to that but at least i didn't have a wreck
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Could the control arm possibly be a reason the brakes lock
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I have the same problem with my truck. Had to replace booster because of a power steering leak. Once I replaced the booster the brakes started locking up. I replaced the booster 3 times. I replaced both front calipers twice and it still locks up. I didn't replace the rear calipers yet. Master cylinder was also replaced. Anyone have any ideas?
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That colould be definitely caused by contaminated brake fluid. I had that once on a other car.
It can not be air in the system.
To explain: Brake fluid is hygroscopic. That is necessary, because it would be dangerous, if you have water in the system. That is why you should regularly exchange the brake fluid.
If the fluid is to old, contains to much water, than after a while of driving, the water turns into steam at the brake caliper. That pressure close the brakes.
After waiting a certain time, when it cooles down, the pressure releases.
So exchange fluid and bleed the system and your problems will disappear...
Sorry for my bad English. I am German...
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I totally agree with you. Unfortunately, many people do not know that contaminated brake fluid can cause a lot of problems, so there is an opinion that it should be changed at least once after the replacement of the brake pads, and if you live in a mountainous area, every time along with changing the brake pads. In addition to transmitting power from the brake pedal down through the hydraulic circuits of the brake actuator, the brake fluid also acts as a lubricant for the brake components, providing them with corrosion protection and reducing friction. And according to the laws of physics, where there is pressure and friction, there is also heat, and of course, it deteriorates also because of that and performs its functions poorly.
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I would check is that you do not have the master cylinder over filled as this would not allow for the natural expansion in the brake system when it gets warmed up. Although quality brake fluid should not expand until temperatures reach around 500 degrees, if someone put a lower grade brake fluid in your vehicle, this could also cause this.
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Never heard something like this. First the reservoir of the master zylinder is not airtight, because temperature, wear of the brake pads which forces the pistons in the calliper to move out, which leads into more needed brake fluid in the system and therefor less fluid in the master zylinder, leads into change of fluid quantity in the master zylinder. If the master zylinder would be airtight the system would not work by design. To much fluid would simply come out at expansion. That could not cause this problem. Lower grade brake fluid in the system? How likely is that? More likely is, that the fluid is old and full of water...
Let's not forget these vehicles are old, and could have rusted brake lines somewhere. What do the hard lines look like? The abs module is located inside the frame under the driver's door. Follow those lines and inspect the condition.
Are the rubber brake hoses original? Do they look to be in good condition? Not swollen or cracking?
I had the same error shortly after getting my 04 back in 2018, and replaced the front wheel hubs. Haven't had an issue since.
Are the rubber brake hoses original? Do they look to be in good condition? Not swollen or cracking?
I had the same error shortly after getting my 04 back in 2018, and replaced the front wheel hubs. Haven't had an issue since.
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