ABS help. 03 Envoy

[jpwalt1987]

Hey guys, I didnt know which forum to put this is so I understand if it needs to be moved. I am trying to diagnose a brake problem on my Moms 03 Envoy. The brakes are staying applied only at certain times. Every time that I drive it everything is all good. She needed the front pads replaced last week so I changed them out. She was having this problem prior to me changing the pads. When I pressed the caliper piston back into the housing it was nice, smooth and easy with and without the bleeder open. That tells me that the calipers and hoses are OK. I can see where the front rotors are getting really hot too. My Mom said that when she was getting on the interstate that she had the accelerator to the floor and the vehicle was only getting to 30 then 40 mph. Engine working very hard. She finally got to 55mph a good bit down the road. Has anyone had any experience with the ABS system keeping the brakes engaged? I have looked all over the internet for tsb's and have not found anything useful. I really dont want to buy unneeded parts. Any help would be great.

 

[KILL4PEACEUSMC]

check the master cylinder for contamination i.e. power steering fluid, motor oil, if the rubber under the cap is baddly deformed ( swollen ) you got a BIG problem. If anything other than brake fluid is in the system, everything that has rubber will need to be replaced. also to help verify problem, after driving the truck, open up the bleeder and see if brake fluid squirts out under pressure or comes out normal (dribble) if it comes out with alot of force, you may have ABS issues.