Brakes sticking

[Robmoo]

I'm having a rather frustrating intermittent issue which I believe is being caused by the electronic brake control. It starts out with the brake pedal getting extremely sensetive and braggy. Then the brakes stay semi-applied and the stabilitrak light and the stabilitrak service light go on. I've checked the ground on the frame under the driver's side. I've gone to Autozone to check for code and they found none. Their code reader won't read ABS codes. What is my next step? The car become almost undriveable. Next time it happens I may try pulling the fuse on the ABS and see if the brake at least release. We have to take a trip to Vegas in June and I can't trust this vehicle "as is."

Any help would be appreciated.

Thanks!

 

[Wooluf1952]

Welcome

In case you haven't
heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/



What are you driving.

 

[Robmoo]

2006 Envoy 4x4 I6

 

[fadyasha]

2006 Envoy 4x4 I6

I had a similar issue but wasn't electronic. When i'd apply the brakes the rear left wouldn't release and the reason for that is the inside of the hub mechanism was messed up preventing the brake from going back in it's released form. What I did was take some sandpaper and smoothened out the inside where felt necessary. Put together the brakes and it pressed normally and released normally with no barriers.

I hope I made sense. I'm not really familiar with all the terms yet haha! We have our own terms in the Middle East

Here's the pic of the complete assembly and where the arrow is pointing is what was causing the problem. I used some sandpaper on the inside of that hole
Not sure if you're is the same problem but it's a start.

 

[The_Roadie]

...Next time it happens I may try pulling the fuse on the ABS and see if the brake at least release. ..

Good first step. The ABS valves may be sticking, and they're tested when you start the vehicle. Could be an electronic problem - could be mechanically sticky valves. Have you ever flushed and replaced the brake fluid? Have you or anyone done a brake job, and pushed the pistons back in WITHOUT opening the bleed valve on each caliper to let the fluid out? I've read a few members do brake jobs the old fashioned way before there were ABS systems, and the old way of just pushing back the pistons ends up pushing possibly dirty fluid BACKWARDS past the ABS valves, putting them at risk. Your root cause may be in the maintenance history.

I had a similar issue but wasn't electronic. When i'd apply the brakes the rear left wouldn't release and the reason for that is the inside of the hub mechanism was messed up preventing the brake from going back in it's released form.

The brakes are in no way connected to the hub the way you show. Sorry. That area is where the splined end of the axle goes. Did you do it, or did some local mechanic just tell you that after they messed with some OTHER part of the system? Brake pads that fail to retract are involved in rough parts of the caliper housing or the piston seals. Or the emergency brake system could have a problem with the drums or shoes not retracting. Not the bearing hub.

 

[fadyasha]

The brakes are in no way connected to the hub the way you show. Sorry. That area is where the splined end of the axle goes. Did you do it, or did some local mechanic just tell you that after they messed with some OTHER part of the system? Brake pads that fail to retract are involved in rough parts of the caliper housing or the piston seals. Or the emergency brake system could have a problem with the drums or shoes not retracting. Not the bearing hub.

While reading that I felt my boss was talking to me and was kinda worried about replying ! A local mechanic did it of course, the problem I was facing is that when I took out the rear brakes for replacement it was lock tight and couldn't release the pressure to put in the new brakes. It was plain stuck. Called over the mechanic he tried to release the pressure and nothing worked. Then noticed that something was jamming it and turned out to be that or something similar ! A little use of sandpaper and no longer jammed.

I'm not certain if thats the same part you're referring too cuz this was facing towards the outside and not the inside. Maybe I got the wrong picture up.

 

[Robmoo]

At 46k the brakes have never been serviced. There is still plenty of pad. I'm not sure if Carmax changed the brake fliud or not. I bought the vehicle with approx 34k miles on it.

 

[Indybp57]

I agree with Roadie, no way the hubs are involved. You didn't say if you thought all 4 brakes were stuck or just one wheel. If it's just one wheel then check the guide pins that hold the caliper to the mounting bracket. I had one of those seize on me. If it's all 4 then its something that would be common to all, like the ABS system, master cylinder, etc. I have noticed on occasion a binding feel in the pedal itself. Could it be a case of the pedal arm binding and not allowing the pedal to retract?

 

[Robmoo]

It was all 4 and the brake pedal wasn't binding. I final bit the bullet and took it to a local GM dealer. They tried reflashing the EBCM and then they ended up replacing it.

 

[Indybp57]

It was all 4 and the brake pedal wasn't binding. I final bit the bullet and took it to a local GM dealer. They tried reflashing the EBCM and then they ended up replacing it.

Ouch! I bet that hurt the pocketbook.

 

[Robmoo]

Yep, $1000 and the problem reoccured. They are looking at the master cylinder now. I've read a few people with this problem where it didn't go away until they replaced the master cylinder. I don't know how much this one is going to cost.

 

[Robmoo]

Got the Envoy back today. They checked out the Master Cylinder, but did not replace it. They gave me a loaner car to drive the last 3 days. I was expecting to pay for a couple of hours labor for all their trouble, but they didn't charge me a thing. I drove the car 18 miles and couldn't get the problem to reoccur. I've got my fingers crossed. I've read horror stories of part after part being throw at this problem without a solution. I have to say my local GM dealership has treated me right and given excellent customer service. I just hope the problem is solved.