[mehmetx]

Hello

My car is F30 2014 3.20ied with 1.6 liter 4 cyclinders engine.

My car applies brake when the windshield wipers are on while moving with speeds above 80km/h. It makes me lose 10/15 km/h speed. The braking is not harsh and the duration of the braking is 2-3 seconds. Cruise control on or off doesnt make any difference. The problem is repeatable.


I have searched the forums and some people point it to brake drying feature. The solution is suggested as dsc/abs ecu change, brake hydrolics change, abs hydro pump change or disabling it via software modification. None of these solutions is certain.

Does my car have brake drying feature?

How can this problem solved?

Please dont say dsc/ abs ecu needs to be changed

None of the technical services in my country has an idea. Im feeling very desperate.

Note: My car has rain / light sensor

[im_an_alien]

This is normal, some BMWs apply light braking to keep the brake rotors dry after x number of windshield wiper wipes. It should not be dramatic enough to show you down though. This is done to keep the brakes ready for immediate action in wet weather

[mehmetx]

Originally Posted by im_an_alien

This is normal, some BMWs apply light braking to keep the brake rotors dry after x number of windshield wiper wipes. It should not be dramatic enough to show you down though. This is done to keep the brakes ready for immediate action in wet weather

This is the brake drying. But i shouldnt feel that brake. What i feel is definetely not normal.

[chowser51]

Have you visually and physically inspected your brakes to make sure nothing is wrong there?

I think you can code the duration or something.

[Wires]

BMW's will drag the brakes a bit to dry the pads and rotors, but not once have I ever noticed it happening, only that the brakes do grab instantly when I manually apply them later.

If it's dropping speed, then something seems off for sure.

[dmaxdmax]

Check your pads for wear. One may be hanging up.

You can also just drive at speed for a while and pull over without using the brakes to see if one rotor is hotter than another--in which case it isn't a 'system' thing, but just a caliper.

If so, take it apart, check it out, maybe replace or rebuild, but at least, clean up and grease as appropriate.

[HighlandPete]

Definitely fits 'over pressure' braking, during the brake drying function. If by repeatable, you mean about every 90 seconds, then that is definitely indicating it is happening during brake drying.

Pressure should be only about 1bar, unnoticed by the driver. Does the car immediately 'free up' after the couple of seconds of retarding? Or is it dragging?

[mehmetx]

Originally Posted by HighlandPete

Definitely fits 'over pressure' braking, during the brake drying function. If by repeatable, you mean about every 90 seconds, then that is definitely indicating it is happening during brake drying.

Pressure should be only about 1bar, unnoticed by the driver. Does the car immediately 'free up' after the couple of seconds of retarding? Or is it dragging?

By repeatable, i mean braking occurs whenever i turn on wipers. Furthermore, when wipers are on and the speed is above 80km/h, auto braking occurs every 20-25 seconds.

When the car brakes itself, it doesnt allow me to accelerate for that 2-3 seconds to compensate the braking even tough i hit the acceleration pedal.

After that 2-3 seconds of auto brake, it frees up and i can accelerate again

[HighlandPete]

Originally Posted by mehmetx

By repeatable, i mean braking occurs whenever i turn on wipers. Furthermore, when wipers are on and the speed is above 80km/h, auto braking occurs every 20-25 seconds.

When the car brakes itself, it doesnt allow me to accelerate for that 2-3 seconds to compensate the braking even tough i hit the acceleration pedal.

After that 2-3 seconds of auto brake, it frees up and i can accelerate again

What you are experiencing would definitely appear to be linked to the brake drying function. It fits with the technical descriptions.

I suggest that the pressure application is too high. As said in my previous post, it is only supposed to be ~1bar, not enough to be noticed by the driver.

The exact cause... I can see your problem, with the average garage. Needs someone who really knows the braking (and ABS) system design/function. Follow the trigger sequence and where there is a possibility of the pressure regulation being misapplied.

[drdino]

Have you changed anything in the brake system or is it compete stock? Is there a chance that a caliper is sticking ?

[mehmetx]

Originally Posted by drdino

Have you changed anything in the brake system or is it compete stock? Is there a chance that a caliper is sticking ?

Everything is stock, nothing is modified. I will have the calipers checked asap. But there is not any problem when i apply brakes by myself. If the calipers sticked, wouldnt i feel problems when i brake?

[PK2348]

Originally Posted by mehmetx

By repeatable, i mean braking occurs whenever i turn on wipers. Furthermore, when wipers are on and the speed is above 80km/h, auto braking occurs every 20-25 seconds.

When the car brakes itself, it doesnt allow me to accelerate for that 2-3 seconds to compensate the braking even tough i hit the acceleration pedal.

After that 2-3 seconds of auto brake, it frees up and i can accelerate again

You should still be able to accelerate even with brakes applied, could it possibly be coming from traction control malfunction?

[mehmetx]

Originally Posted by PK2348

You should still be able to accelerate even with brakes applied, could it possibly be coming from traction control malfunction?

If it were so, wouldnt i be experiencing the problem when the wipers are off?
Everything is perfect when the wipers are off.

When brake drying does the car cut throttling even though the pedal is pushed? Is the normal brake drying fuction working this way?

[BWbimmer]

Did you get the error log read?

[HighlandPete]

Originally Posted by mehmetx

Everything is stock, nothing is modified. I will have the calipers checked asap. But there is not any problem when i apply brakes by myself. If the calipers sticked, wouldnt i feel problems when i brake?

My trouble shooting path would 99% eliminate the calipers, due to it only happening when the wipers are on and the 'link' is to the intermittent brake drying function.

[HighlandPete]

Originally Posted by mehmetx

If it were so, wouldnt i be experiencing the problem when the wipers are off?
Everything is perfect when the wipers are off.

When brake drying does the car cut throttling even though the pedal is pushed? Is the normal brake drying function working this way?

Should not be noticed by the driver, as it is only like applying the brakes with a feather light touch.

To quote BMW:

The driver notices no deceleration or noise.

Whatever is wrong could be applying some ABS/DSC intervention. If so, that could be influencing TC.

[mehmetx]

Originally Posted by BWbimmer

Did you get the error log read?

Yes i had it checked, especially the dsc. No error log at all.

[mehmetx]

Originally Posted by HighlandPete

My trouble shooting path would 99% eliminate the calipers, due to it only happening when the wipers are on and the 'link' is to the intermittent brake drying function.

Next week im going to technical service and im gonna teach the brake drying function to them as they seem they dont know this feature. First thing will be brake system inspection including calipers.

At the moment im praying that it wont require dsc/abs ecu change as they cost a lot (

[mehmetx]

Originally Posted by HighlandPete

My trouble shooting path would 99% eliminate the calipers, due to it only happening when the wipers are on and the 'link' is to the intermittent brake drying function.

Next week im going to technical service and im gonna teach the brake drying function to them as they seem they dont know this feature. First thing will be brake system inspection including calipers.

At the moment im praying that it wont require dsc/abs ecu change as they cost a lot (

[mehmetx]

I have driven like 20 minutes and didnt brake by myself too many times, it was like 3-4 times braking. When i stopped, i checked the rotor temperature by touching. They are much hotter than my body temp. I guess they are above 50 C degrees Celcius (122 degrees Fahrenheit). The ambient air temp is around 9 degrees Celcius (48 Fahrenheit) degrees and it was raining.

I suspect that calipers are sticking to the rotor and making it heat up. And eventually this causes a lot harder braking than its supposed to be during brake drying. Am i right?

[HighlandPete]

Originally Posted by mehmetx

I have driven like 20 minutes and didnt brake by myself too many times, it was like 3-4 times braking. When i stopped, i checked the rotor temperature by touching. They are much hotter than my body temp. I guess they are above 50 C degrees Celcius (122 degrees Fahrenheit). The ambient air temp is around 9 degrees Celcius (48 Fahrenheit) degrees and it was raining.

I suspect that calipers are sticking to the rotor and making it heat up. And eventually this causes a lot harder braking than its supposed to be during brake drying. Am i right?

Simply stated, no.

There will be heat from any braking. Your description appears totally normal for the conditions. What you'd be looking for, is likely one caliper sticking and a lot of heat (untouchable) in the rotor/disc. But you'd feel that from any braking, given what you report for the retarding experienced.

If you didn't have any feeling of sticking brakes after braking, the actual brakes aren't likely any part of the issue you are experiencing.

Think "switching on wipers", and its related function to the braking system, that is your biggest clue to tracing the fault.

[bellguy]

Exactly this

Only does it when wipers are on means absolutely it is an issue with the dry braking system, might be possible to code the amount of pressure exerted on the calliper pistons by the ecu.