Mercury Grand Marquis auto won't shift into gear

[Jobe72701]

My mother's 1996 Mercury Grand Marquis LS automatic won't shift into gear. She says that she has to pump the breaks dozens of times before it will shift out of park. Sometimes while pumping the breaks it will almost go to the floor, then you can shift in gear. Someone thought it was pressure related and that breaks/shifting was interconnected. Break fluid was added and it made no difference. They tried messing with the linkage under the dash, but it didn't help much. Any ideas?

[chino]

Bleed the brakes to get good pressure and all the air out.. try it if that doesn't work you've got me.. and it almost sounds like she has a hole in one of her break lines

[BDP]

I will ask Lazarus and see what he thinks since he is the Ford Technician!

I would think (but not upto date on Ford Motorcrafts Technology) that it Would be that Safety Brake linkage connection that is on the brake peddle. That of course would only allow it to not shift out of park.

If there are other shifting problems, it is prolly not connected to the Brake peddle. I am supposing the shifter is on the column. If the car has high milage, there could be some debris under the dash causing the linkage to not move properly, but I doubt it since ford usually incases all of their sensitive stuff in sleeves.

Perhaps it could be something electronic after all, I will ask Lazarus and if he has no idea, I will look info up about it. Maybe there is some sort of shifting solenoid in the column that keeps the gear selector from moving if the brake is not depressed (during all gears) - that wouldnt make since, but its a ford after all. If thats the case, it could be a faulty connection to a switch circuit under the dash located on or around the brake peddle assembly prolly on the firewall side.

Some Police Cruisers have a small cable that connects to the brake peddle that opens a vacuum canister - Why? I have no idea, I saw it once when I was installing some Code 4 lights. But I doubt that would be connected to a Shifting Device! :surp:

Try pushing the peddle to the floor and holding it, then wiggle your food to make the peddle go from side to side. This could possibly let you detect a wiring problem with a switch.
Also look to see if clutter could have fallen into the shifting linkage somewhere that could block the travel or movement. Check to make sure the brake lamps function too :P

Good luck with it :thumbup:

[BDP]

Originally posted by sleeper@Apr 10 2004, 03:06 PM
.. and it almost sounds like she has a hole in one of her break lines
Not necessarily a hole....

On the automatics, most have brake boosters that house around 4 - 6 peddle pumps of pressure. Most likely if the peddle travels to the floor after a few pumps or rappid pumps, it is a brake booster problem or vacuum issue. Another thing is that the master Cylinder will also have faulty o rings from time to time allowing fluid to bypass certain valves which will cause the peddle to travel further and faster.

Not all cars are the same of course, but most function about the same.

If there was a massive hole, it wouldnt ever hold pressure in the line. Something that would leak slow enough to feel the pressure weaken in the lines would be something like a wheel cylinder on the rear drums. The have a rubber head that becomes warn or too hot and it will crack or get torn and leak small amounts of fluid onto the drum/wheel well in turn letting air into the system on peddle release.

[Jobe72701]

It turned out to be an electrical problem with the brakes, which caused the shifter to lock. Thanks for the help!

[Mr. Merk]

Originally posted by Jobe72701@Apr 16 2004, 01:57 PM
It turned out to be an electrical problem with the brakes, which caused the shifter to lock. Thanks for the help!
glad you got the problem solved :thumbup: