Brakes Lock Up

[bams50]

Help...This morning again as I went to stop, my brakes were 'locked' - peddle was hard and would not go down at all - and I could not stop, had no brakes at all. This has happen before and I talked to several garages now and none seem to be able to solve the problem. I had to booster replaced about a year ago. This problem has been on & off for a while but seems to be getting worse. Other times the peddle will go all the way to the floor. Can someone help me? i have a 1990 Mark VII. Thanks! [img]images/smiles/icon_confused.gif[/img]

[bams50]

ITS HAS ABS - NOT SURE OF THE STICKING RELAY....I JUST TALKED TO ANOTHER GARAGE AND HE SAID HIS FRIEND HAS A MARK VII WITH THE SAME PROBLEM; HE RECOMMENDED BLEEDING THE BRAKES....

[Clemens]

i don´t know how it´s set up on your actual ride, but could it be something with the linkage and or the rod that actuates the master cylinder?

just a thought, but worth considering...

[Avenger]

I don't know much about 90's cars, but I would think that you have a brake hose that has collapsed internatlly and not allowing fluid to return once the pedal is no longer depressed, the car is twelve years old and brake hoses last about 6 before they fail. DouglasR

[Lugnut]

Mark VII brakes are a pain in the butt! There are two relays involved along with an ABS sensor and a pressure sensor. Diagnostics start with a definition of which of the brake lights come on and stay on or are intermittant. Then there is the pressure tank that can also go South.

Do not attempt to bleed the brake system unless the pressure is off of it.

Actually, I wouldn't let anyone touch the brake system on a Mark VII unless they were a Ford certified brake technician at a Lincoln Dealer. Too many things and phantom failure indicators to deal with on a shadetree mechanic basis.

[Dan Szwarc]

ABS? Do you have a sticking ABS relay?

[BLUECOLLAR]

Field, it doesn't sound to me like the brakes were actually "locked up". When I hear "locked up", I think of the wheels being locked and not releasing.

I think your problem may be a booster problem. Check out this link on my site: http://www.americanairsuspension.com/BRAKES%20MK%207.htm

[jz78dje]

With respect to the ABS, I guess it's not impossible, but seems unlikely. I don't think the ABS unit can actually hold the brakes on, it can only pulse them so you should hear the ABS motor running if this is the case. Also, if there was a stuck relay the ABS module should be able to recover from this problem by disabling the ABS system.