I have a 2002 Chevy Avalanche. Several months ago after driving for an hour or so, I stopped at a home center, when I got back in my truck and started it the brake pedal dropped almost all the way to the floor. I felt like I had enough brakes to get me home so that’s what I did. The next morning I took it to my regular service technician. They couldn’t get it to recreate the problem, but to be on the safe side they advised me to have the master cylinder replaced. They replaced the master cylinder and it seemed to resolve the problem, but a month or so later it did it again. I took it back to the shop but once again it wouldn’t recreate the problem, but the brakes were working fine. It happened again yesterday while my wife was driving, we really don’t feel safe driving. The problem seems to only occur after we drive for an hour or so, and it still has some brakes,but the pedal drops very close to the floor. Do you have any insight to what the problem might be.
Thank you for any assistance.
Since it is an intermittent issue, I would say it is electronic and most likely your ABS system.
Since it only occurs after a long drive, it could be a heat-related problem, requiring cooling down. Could a heat-shield have failed causing some brake fluid to vaporize ?
Thanks for the advice, I’m not getting any warning lights on the dashboard,but if it is the abs system is there a fix for that.
You need a high level scan tool (that can read ABS codes) to find out the issue.
Thank you. I‘ll look for a mechanic that has one
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It could be the main diaphragm in the booster is torn. Even a new master cylinder wouldn't fix this.
Thanks, I’ll pass that information on to my service technician. They apparently don’t have a scan tool that can diagnose an abs malfunction and like I said in a previous post I have never got any warning lights on my dashboard. So this might be something they can look into.