My brake pedal in my car suddenly starting going all they way to the floor

Hi,

If the pedal is going to the floor, chances are either you have brake fluid leaking, the fluid is low, or the master cylinder has gone bad. If the fluid is full and there are no leaks, it's most likely the MC.

Take a look through this link:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

I suspect the vibrating is the ABS actuating. If you determine the MC is the problem, here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

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Here are the directions specific to your vehicle. The attached pics correlate with the directions.

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2002 Volkswagen Golf GL (1J1) L4-2.0L (AVH)
Removing and Installing
Vehicle Brakes and Traction Control Hydraulic System Brake Master Cylinder Service and Repair Procedures Removing and Installing
REMOVING AND INSTALLING
Brake master cylinder
Special tools and equipment required

pic 1

3094 Hose clamps or equivalent

Removing
Obtain radio code on vehicles with coded radio.
Disconnect battery.

pic 2

Disconnect or connector -1- of Mass Air Flow (MAF) sensor from air filter tube.
Remove bolts -2- at air filter -3- and move filter to left side.
On vehicles with Diesel engines, remove relay panel above brake booster.
Spread sufficient lint-free cloths in area of plenum, and on engine and transmission to catch any escaping brake fluid.
Using a bleeder bottle, draw off as much brake fluid as possible from brake fluid reservoir.
Clamp clutch master cylinder supply hose with clamp 3094.
Remove clutch master cylinder supply hose from reservoir.
Disconnect brake fluid level sensor wiring connector.

Vehicles with automatic transmission

pic 3

Disconnect wiring connectors from pressure sensors -a- and -b-.

All vehicles
Disconnect brake lines at brake master cylinder and seal with plugs from repair kit, Part No. 1H0698311 A.
Remove nuts securing brake master cylinder to brake booster.
Remove heat shield if installed.
Carefully remove brake master cylinder from brake booster.

Installing
Install master cylinder in reverse order of removal.

Observe the following points when installing:
When connecting brake master cylinder and brake booster, be sure that push rod is correctly located in brake master cylinder.
After installing, bleed brakes.
Restore basic setting.

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Let me know if this helps or if you have other directions.

Joe

More than likely you have a leak. Have you found any fluid on the ground?

If not, then I suspect the hydraulic unit is leaking internally.

Clearly we need to check out the basics. Here is a guide that will run through the most common causes. Let us know what you find.

I also attached some generic info about your brake system just to get us started.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor