Working through a few issues at the moment, one of which is my brake pedal "dropping" almost as though its being drawn or sucked down. If I start the car all is good, but then the brake pedal drops as described, resulting in the brakes being applied, albeit gently. It's enough to prevent the car from moving forward when the park brake is released. I can pull the pedal back up with my foot and the car rolls forward. However once I start driving it happens again. This has resulted in me driving with my left foot (RHD) holding the brake pedal up. Brake fluid is fine and I recently replaced the brake switch also.
Any thoughts much appreciated. 09 XF.

 

So did you have this problem before replacing the brake switch? If not did anything get changed during the switch change out? For example did you adjust the push rod?

 

Yes, the problem was there before the switch was changed. I didn't adjust anything in the process. Changing the switch was awkward, access wise, but it didn't affect anything else. Thanks for the response.

 

Any takers? I've seen mention of the possibility of adjusting the plunger behind the brake pedal, but I can't see how it would have moved so far away from the pedal. Any thoughts would be very welcome.

 

You could try backing off and/or tightening the nut on the end of the push rod---just keep count of the number of rotations so you can return it to as found.

 

Thanks. I was considering that as an option. I'll update after I check it out.

 

The brake pedal going to the floor is a serious situation and should be looked into ASAP.

Often the cause for that situation is air in the brake lines or a failing master cylinder. You say you are working on a few things on the car. What have you done so far?

Just a side note the brake switch at the pedal is not what controls the start issue it is a pressure sensor on the ABS that controls the start.

 

When I say my pedal drops, I'm talking by about 1/2". It's enough to apply the brakes gently enough to cause a drag, as opposed to bringing the car to a dead stop. The other issue is the old chestnut of the gear selector dial not rising. I can still rotate it and select gear so I can live with that for now. Prior to changing the brake switch, the dial wouldn't rise and it was stuck in park. Coincidence or not, changing the switch made a difference of sorts.
Thanks for the input.