Hi all, been having this problem for a while now and thought I'd jump on here and see if anyone can help me out?

After a few minutes of driving without touching the brakes I have noticed that they will then start applying themselves. If I depress the brake pedal then release it the brakes release again and the car will drive fine but after a few more minutes they will do it again? The rear brake lights also come on while this is happening.

I have taken this to a garage to be looked at (not a dealership) and they have tried the following:

New master cylinder
Changed brake fluid
Refurbished front and rear brakes (calipers etc.)

The car is not reporting any fault codes?

I have done a make-shift fix by putting a bungee cord around the brake pedal and the steering colum to hold the brake pedal up, as I noticed that there was a little bit of 'play', and thought maybe the pedal was very slowly going down by itself over time. The brakes are still slowly applying themselves but not as servere as before.

Any help would be greatly appreciated.

Thanks!

Sorry, forgot to mention it's a 1.9 sporting JTD if that helps?

There is a similar thread relating to brake light switch on here somewhere. Have you had a new switch recently? If so, this could need resetting as it may be pushing the pedal.

More likely is a servo fault. When the pedal is pushed, a valve in the servo allows atmospheric pressure into the servo behind the diaphragm and with a vacuum in front of it, the pressure helps move the piston, increasing the effective braking pressure. When you release the pedal, vacuum is applied to both sides of the diaphragm, so both being equal, there is no effect, so allows it to release.

My guess is that the valve inside the servo is leaking, allowing the servo to apply the brakes. When you press the pedal and release it temporarily equalises the pressures until the valve leaks again.

Have a look at Eper and identify your part number, then search internet and suppliers for best price. Hopefully you may be able to find someone who can refurbish it, used to be common with Lockheed and Girling units. Good luck.

Thanks for the info, will investigate further and get back! : )

Well I've had the servo replaced and had a new brake light switch fitted and it's still doing it. Not good! Thanks for the suggestion though! Really racking my brains here...

Have a look at this thread and try adjusting the switch as described later in the thread.
https://www.fiatforum.com/stilo/333637-brake-pedal-keeps-brake-lights.html

The brake lights no longer stay on, I have bought a new switch and the lights are now fine, it's just the problem with the brakes slowly applying themselves now, but thank you for the info : )

Ive had this exact problem ..

i seem to have sorted it by blanking off the EGR valve
mine was feeling as it was holding brakes on and the drives side rear disk would get quite warm

blocked the EGR off and it dosnt seem to do it , but avnt drove alot since ive done it

Car is fixed! Turns out it was an adjustment by the master cylinder (?) in the passenger footwell that just needed tweaking... thanks for the help though guys!

Hi!

What sort of adjustment?
Can you explain better?

I have the same problem and the brake system was already checked by different professionals and they can't find the problem.

My regards

pgainf said:

Hi!

What sort of adjustment?
Can you explain better?

I have the same problem and the brake system was already checked by different professionals and they can't find the problem.

My regards

Click to expand...

I assume being in Portugal, your car is Left Hand Drive (LHD), so the above may not apply, or may be different. Many cars are engineered for LHD and when built as RHD instead of relocating the brake master cylinder to the right side, there is a linkage under the dash that takes the pedal movement to the left side of the car. The rest of the braking system remains identical. This linkage has to turn the pedal movement from forward to sideways across the car, then forwards again at the master cylinder above the left footwell. This linkage will have an adjustment facility and it would appear that on UK cars this sometimes needs resetting.

Your pedal probably goes straight into the master cylinder, so the problem is more likely to be the brake light switch, as described earlier in this thread and in others. Try removing the switch and see if this helps, but be careful as your brake lights will no longer warn following traffic, so test it at a quiet time.

Thanks for the reply!
The car is LHD.

I only feel the car braking a bit when the brake light switch is installed.

I already shaved a bit the tip of the brake switch and it almost fixed the problem, but not to 100%. The brake stop lights will work fine.

Things done until now:
Brake tubes changed, brake oil changed 2 times, 4 different brake switches, brake system inspected. New brake pads and discs installed.

It does the same even when the electric plug is not connected to the brake switch, so it must not be an ABS / electronics problems. No ECU / OBD errors.

Do you thinks I might need a new Master Cylinder?
Servo valve leaking?

The car breaks and runs great without the Brake switch installed.

Before the brake tubes where changed the car would brake itself until stopping completely or would be like driving with the handbrake on.

My regards