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Discussion Starter · #1 ·

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.
 

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Brake Booster is probably bad. I had this issue on my 2009 Jetta SE. It started out with my brake lights coming on and staying on, and my daytime driving lights wouldn't come on. They replaced my booster, then my master cylinder failed, and the booster failed, it caused my brakes to drag so much my car would barely move. I will also say that I originally went cheap and used after market parts, recommended by my local mechanic, ended up putting in OEM VW parts and haven't had an issue since. I noticed after all the work that my brake pedal rode higher, which I think put it above the pedal sensor so the brake lights didn't intermittently get stuck on anymore. Good luck!
 

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Discussion Starter · #3 ·
Thank you for the reply.

I am pretty sure that my brake lights are lit all the time, but have not yet been able to verify that. I tried to find a fuse that will just turn off the brake lights but had no luck. Probably disconnecting the brake light switch would tell the tale, but it is really buried in the engine compartment up against the firewall under the master cylinder and I can hardly get a hand on it no less figure out how to disconnect it blindly with one hand...
I spoke to the mechanic that changed my master cylinder and he has done some reading since I told him about the brakes dragging, he found several stories about bad boosters or the internal spray in booster breaking causing brakes to drag. He advised me to disconnect the vacuum line that feeds booster the next time this happens to see if that frees up the dragging. Tomorrow I will figure out how to disconnect that vacuum line and then take the car out and try to reproduce the problem.
Just realized that you mentioned your DRL was not working. I have not checked my DRL, but the DRL light has been lit on the dashboard, so it stands to reason that my DRL probably is not working. At the moment I am driving in the dark and the DRL light is not lit on the dashboard for the first time I can remember.

Thank you again for your reply. Between you
And my mechanic I now have greater insight into the problem.


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Good to hear!
DRL should be off if headlights are on.
DRL should be on if the engine is running and the parking brake is off.

You could also check the brake pedal position sensor if your brake lights remain on.

It was a really odd one for me and the brake lights staying on plagued me for months before I went for an oil change and needed new calipers because my brakes had likely been dragging and I didn’t know it.
 
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