Picked up a used '09 Jetta V 5cyl /Auto with 115K miles on it. (Fun car!)
I didn't like how the brake pedal felt (soft, and fading slowly to floor with some effort) so I had a mechanic change the Master Cylinder.
After (?) the Master Cylinder was replaced, the brakes began dragging intermittently.
On advice of others, I (DIY) changed the rear Calipers, and brake hoses. No joy, Still intermittent dragging. The problem seems to be happening more often recently, and I have determined that it effects one or more (all?) calipers randomly. I drove the car with the ABS system disabled (By pulling the 2 ABS fuses) and problem still happened.
On searching here and elsewhere, I found many Jetta IV/Golf IV problems similar to mine but no Jetta V/Golf V problems. Armed with info from My search readings, I have found that if I lift the brake pedal, the dragging goes away. I have also discovered that the brake lights do not light and the Cruise Control is not functioning. My brake light switch is in the engine compartment, and was not replaced when the Master was swapped.
There is very little play in the brake pedal when you pull up on it, but I have cleared the dragging on the last 3 occurrences by pulling up on the pedal with my foot.
It seems that the brake light switch needs replacement to restore brake lights and Cruise, but how could that cause the brakes to drag?
Is there some adjustment that can be made to the pedal/Master cylinder assembly to solve the dragging problem and maybe the brakelight/cruise problem?
Any words of wisdom would be greatly appreciated.