hi all ...iam new to GMTNATION from TRAILVOY ,i have an older gmc 03 envoy xl sle and i just want to let everyone share my problems with the abs brakes. The innitial problem was the brakes were very spongy so i replaced the pads and the rotors thinking that was it , no way they were still spongy so i took it back to the mechanic and after acouple of hours he said it was the vacuum booster unit (about a 400$ job) here in Canada. Time for another opion so i took it to master mechanic and they tested it and cam up with a abs pressure control module failure error as it turned out that was the problem (1300$ Canadian parts and labor ....would like to hear feedback from trailblazer and envoy owners as i hear this brake problem is common........thanks all great site ...hommer
spongy brakes 03 envoy xl sle
- Thread starter hommer
- Start date
Welcome! All of our brakes feel spongier than other vehicles. Don't spend money on them unless you see a functional problem. Make sure they are properly bled INCLUDING cycling the ABS valves.
Juicy K
Member
I know this thread looks dead, but in case somebody comes across it. When my father was test driving 02' Silverados (NEW at the time) that was his only complaint. He ended up buying one, they have always felt that way. I just wonder if its the way GM went about switching from Front Disc/Rear Drum to Front Disc/Rear Disc... My Bravada is not nearly as bad as his Silverado, but I still notice it. She stops great for me. 
Before you spend a lot of money, realize (as others have already said) that the brakes ARE spongey feeling on this platform.
One way to help with the problem is to find some place safe and slippery (grass, ice, snow, gravel, etc.) and speed to 30 or so mph, then sharply press and hold the brake pedal down so that the anti-lock pump cycles. The pedal will feel weird under your foot, you will hear strange noises, etc. (growling, rumbling, shaking), as the anti-lock pump cycles. All of that is perfectly normal but takes the first time user by surprise! Cycling the pump like that will insure that the system is not operating with an air bubble in the extra lines between master cylinder and anti-lock pump and generally firms up brake feel for a while.
For the record, some of us have gone to great lengths to solidify the brake feel on our GMT platform, with varying degrees of success. Mine stops the best it ever has now with 150K miles and my 3rd brake system change, but it is STILL spongey feeling. It is a design issue, not bad parts.
One way to help with the problem is to find some place safe and slippery (grass, ice, snow, gravel, etc.) and speed to 30 or so mph, then sharply press and hold the brake pedal down so that the anti-lock pump cycles. The pedal will feel weird under your foot, you will hear strange noises, etc. (growling, rumbling, shaking), as the anti-lock pump cycles. All of that is perfectly normal but takes the first time user by surprise! Cycling the pump like that will insure that the system is not operating with an air bubble in the extra lines between master cylinder and anti-lock pump and generally firms up brake feel for a while.
For the record, some of us have gone to great lengths to solidify the brake feel on our GMT platform, with varying degrees of success. Mine stops the best it ever has now with 150K miles and my 3rd brake system change, but it is STILL spongey feeling. It is a design issue, not bad parts.
IllogicTC
Member
- Dec 30, 2013
- 3,452
Juicy K said:I know this thread looks dead, but in case somebody comes across it. When my father was test driving 02' Silverados (NEW at the time) that was his only complaint. He ended up buying one, they have always felt that way. I just wonder if its the way GM went about switching from Front Disc/Rear Drum to Front Disc/Rear Disc... My Bravada is not nearly as bad as his Silverado, but I still notice it. She stops great for me.
I think it's part of the package with larger vehicles. While there's a bit more pedal travel for equal response, it feels "linear" to me, which can be a boon for trailer-handling. My woman's Impala is just the opposite - It's either you're going or you're stopping right there.
Juicy K
Member
IllogicTC said:I think it's part of the package with larger vehicles. While there's a bit more pedal travel for equal response, it feels "linear" to me, which can be a boon for trailer-handling. My woman's Impala is just the opposite - It's either you're going or you're stopping right there.
In 2010 while SUV (Before we bought the Bravada) shopping, we had looked at the X5, M Class, XC90 (used of course) and none of them had this problem. But that could be what due to the fact our trucks are the first step out of what I call the American Auto Makers Great Depression. lol
One thing that I have noticed with my vehicle was that I had a significant reduction in sponginess when I put new rear pads on, and this time I used the semi-metallic instead of ceramic. Now, whether that's because of the pads, or that I bled the rear brakes as per normal brake job routine and got rid of an air bubble, unknown. I am curious as to how other vehicles work once new rear pads are put on.
The brakes themselves are adequate on this platform. I am of the opinion that it is the design of the anti-lock pump that gives the spongey feel. Slow steady pressure on the brake pedal while at rest will just about drop the pedal to the floor. No way that can even happen in any other brake system (except of course, others with a similar anti-lock pump) because in a pure hydraulic system once system pressure is reached there is no more travel. In this design it seems that system pressure is never reached because of by-pass in the pump. The only real way to remove the feel is to also eliminate the anti-lock pump from the brake system. It would then firm up just like any other system out there, but there is no need to do so because the brakes DO work and they DO stop if in good condition.