I have had brake issues for well over a year now. My brake pedal occasionally goes to the floor and the brakes fail. When this happens, I have to quickly lift my foot off the brake pedal and slam my foot back down. They then start to work again. This first began in October 2010. I took the truck to the dealership, paid them $850 to fix the brakes. All they did was replace the Master Cylinder. The brakes worked for about a week and the problem happened again. I took the Explorer back to the dealership, they determined they put a bad Master Cylinder in, so they replaced it again at no charge. Again, I drove it for about a week when it happened again Again, I took it back to the dealership. They couldn't find anything wrong with it and sent me home with it. This went on for about 6 months and six more visits. At one point they even told me I was crazy and nothing was wrong with my brakes! Finally on the last visit, they said that yep they felt what I was complaining about and replaced the Master Cylinder yet again! The car actually drove fine this time for a couple of months. This all happened in Jacksonville, FL. In June of 2011 I moved to Mobile, AL. I parked the car and just now started driving it again. Well, guess what! It's all happeneing again! I called the dealership inm Jacksonville and they said that the Master Cylinder was 10 days out of warranty! TEN DAYS! OK, I am so not thinking that my problem is the Master Cylinder now, it HAS to be something else, what are the odds that they put 3 bad Master Cylinders in! I have plenty of fluid, no leaks. The ABS light is on, the AdvanceTrac is off. Those two lights are the same lights that were on when I first took it to the dealership and they said Master Cylinder. My question is, has anyone else had this issue? Brake Booster maybe? ABS system maybe? I don't have the money at this time to just go replacing parts if that's not what the problem is...

 

I am having a similar problem. Have you found anything?

 

I believe you hit the nail on the head with the ABS system.

 

Nope, it is still parked. I moved again, so it was driven the 20 miles where we moved. .The tag is now expired and I am like, why renew it???

I REALLY want/need to drive my car, but don't have any money to put into it! A friend of mine looked at it and said Brake Booster and yet ANOTHER Master Cylinder!

I am STUCK in this house 24/7 because I can't get a job with NO TRANSPORTATION! I have small kids and am scared to take them out in THAT car! She sure is pretty, but other than sell it, I don't know what to do!!!

 

I think that you have a bad sensor for the abs. and most of the time when people put new master cylinders on they don't get rid of all the air that's in the lines as well as in the new master cylinder. I have a question for you when they work and you're stopped at some place does the car or suv start to move with your foot on the brake pedal or does the pedal stay firm?

 

did they bleed the brakes after they put the new master cylinder on ? there could be a air pocket in the brake lines ! even if the ABS was not working you still should have brakes but it,s something to check on anyway ! first i would bleed all 4 wheels and make sure all the air is out, then if it,s still the same then go to the ABS system !

 

Oh yes, the brakes have been bled over and over again. I've heard that one too. Well I have a couple hundred dollars I can "play" with at the end of next month. I think I am going to get a brake booster and yet another master cylinder and get a mechanic friend of mine to put them in for me. I just think there's more to it than that though. I mean how many times can a master cylinder possibly go out!? Thanks for yall's imput!

 

It might pay to hold off on the booster. There is a direct mechanical connection from the brake pedal through the booster to the master cylinder. The booster does just that , boosts. The old story of after replacing a part 5 times applies here , "it ain't that part that's the problem".
There are valves in the ABS unit that could be the problem. They are expensive, but have someone who is experienced with modern brake systems and has the tools to check today's electrical components before throwing any more parts at it.