So my sister was driving her 2007 Mustang Auto (V6, Yes I know this is GT Tech) coming home from work and pulled into her mail box to section to get the mail, did everything normal, put the car in park, turned it off and got the mail.

Came back not a minute later, started the car up, put it in reverse and it went backwards fine but there was NO brake pressure what so ever, she ended up rolling into the back of a curb where she turned the car off.

She started it up 10 seconds later and everything was fine. Any ideas?

 

I thought you couldn't put it into any gear unless the brake pedal was depressed?
What really happened here? It should not have gone backwards until she released the brake pedal or she should have noticed the problem before she put it in gear.
Is she telling everything or is she explaining how she hit the curb?

 

I think you can't change gears without the brake on.

 

LOL At the What really Happened Here statement...

Shes 23 married and one of the most responsible people I know. With that said, the incident happened and she called me up (Im at college about an hour away) and asked me if I knew what could have been the problem- She also said she was taking it to the Dealer Friday but she was nervous the problem would have occured again.

I'll try to get more info, just figured you guys might have a clue or TSB about brakes or something.

 

No idea what would cause that. Brake failure is one thing, but intermittent brake failure is a little bit on the wierd side...

 

Driver error.

 

 

I cannot imagine what could possilbly happen that would cause the lack of brakes (pedal) one minute that would go away and be normal the next minute. Regardless of who's is behind the wheel. But it is true at least with my GT...you cannot shift into drive or reverse without depressing the brake pedal first!! That I am sure of. Our power brakes are boosted from our power steering pump. Check the belt and the pulley on that pump!
Scott

 

It sounds like a possible ABS issue. If I start drifting in my 00 Crown Vic and suddenly stab the brakes, the pedal will drop to the floor. Once the car stabilizes and the ABS/Trac Ctrl takes a chill pill, the brake pedal pressure returns.

 

Hmmm, that's a good thought. My bro-in-law had something like that happen with his Chevy truck. He was pulling into a parking spot and the truck just kept rolling and he hit the wall of the building. Only minor damage but it was still under warranty and GM replaced something in the ABS system. Sorry, don't have the details on the what was actually wrong.

 

That is strange......... never heard of that happening before.

 

I would like to see a picture of this setup since my car has vaccum booster in it.

 

Yeah I think my sister was supposed to take it into the dealership (warranty) yesterday, so Ill get an update soon.

 

The older 4.6 cars (SN95) had the hydraboost. Thats the nice thing about the S-197 all of that lovely engine bay space.

 

Make sure she knows how to properly use an e-brake. She wouldn't have even hit the curb if that was the case.

 

Yep I know but his signature say he has this. Which is why I asked to see it.

2005 Performance White GT Vert Parchment leather interior, side airbags, premium machined 17 inch wheels, shaker 500, IUP dash upgrade, automatic transmission. Ordered on 1/8/05 and arrived on 3/18/05

 

Hey Richard,
Unless your car is like a "one off" it does not have a vaccum booster. These cars have not had them for years. My 96 Cobra had no vaccum booster...it was also powered by the power steering pump. I think you are the one that needs to post the picture.
Scott

 

My specs document says the brakes are operated by Engine Vacuum. I have no idea what that really means though.

 

Scott,

You might want to double-check your car... I think you'll find a nice, thick vacuum hose routing from the back of the manifold (nipple is under the rear of the intake manifold, angled towards the driver's side) that feeds a "T" fitting, with a smaller line heading forward to the fuel pressure sensor, and the other, larger branch, going direct to the brake booster. The PS hoses route from the pump to a half-assed cooler in front of the AC condenser, thence to the rack, and back to the pump again...

 

I guess I will back up and check it out again. I am absolutely sure ( well almost) that my 96 Cobra did not have a vacuum booster and was powered by the power steering pump. The reason is with the 4 cammer engine there was physically no room for the vacuum booster. Maybe I am only half right. I just thought our cars were the same as back than. Can anyone else shed any light on this?
Scott