EPB releasing itself ?

[roydonaldson]

Hi there,

It's weird, I've had 2 occasions now where when sitting in traffic at a red light, where I've pulled up, pressed the brake pedal and the electronic park brake has come on, lights saying it's on etc. Then while I've been sitting, the brake just goes off of it's own accord !

Not sure what's going on. Anyone had this before ?

Roy.

 

[Alan66]

Hi there,

It's weird, I've had 2 occasions now where when sitting in traffic at a red light, where I've pulled up, pressed the brake pedal and the electronic park brake has come on, lights saying it's on etc. Then while I've been sitting, the brake just goes off of it's own accord !

Not sure what's going on. Anyone had this before ?

Roy.

I think you’re activating auto-hold which will release after a set period of time. Auto-hold activated by pressing foot brake, parking brake activated by the EPB switch in centre console


Sent from my iPad using Tapatalk

 

[Matt Titanium]

Do you have Hold Assist and if so, is the green brake light coming on/going out? Or are you talking about the EPB coming on on it's own with the red light coming on and going out? Normal hill hold shouldn't being any dash lights on.

 

[JohnM100]

^This

Red or green illumination is key to advising further.

 

[roydonaldson]

I get a green light on every time I come to a stop and the car holds itself. What has now happened twice is that I've pulled up pressed the brake, the green light comes on and normally this holds until I press the accelerator to take off once more. But twice, it has turned itself off, ie green lght goes out and car rolls all on its own.

 

[JohnM100]

Is the Hold Assist LED on the button next to the EPB switch in the centre console illuminated?

Alternatively how much pressure are you applying to the brake pedal as you stop? I do cadence braking so sometimes once the car comes to a stop I need to put a but more pressure in the pedal to ensure Hold Assist is engaged vs stop & creep. Then foot off brake pedal.

 

[abmat]

I get a green light on every time I come to a stop and the car holds itself. What has now happened twice is that I've pulled up pressed the brake, the green light comes on and normally this holds until I press the accelerator to take off once more. But twice, it has turned itself off, ie green lght goes out and car rolls all on its own.

That is not the parking brake. That is indicated by a red symbol.

what you are describing is hill hold assist which is only active for a few seconds then releases. This is to slow you to transfer your foot from the brake to accelerator when on an incline without rolling before moving off again.

 

[george forbes]

That is not the parking brake. That is indicated by a red symbol.

what you are describing is hill hold assist which is only active for a few seconds then releases. This is to slow you to transfer your foot from the brake to accelerator when on an incline without rolling before moving off again.

Any hill hold assist system should hold until you want to release it not on a time limit, most work by releasing as soon as the accelarator is pressed.

 

[abmat]

No. Read the manual

 

[Mazman]

You definitely have to press the brake pedal as you stop to set 'hill hold'. It then stays on until the car moves off. It doesn't time out.

 

[abmat]

hill hold assist from my A6 manual. Auto hill hold holds it on if switched on.

 

[george forbes]

View attachment 247300
hill hold assist from my A6 manual. Auto hill hold holds it on if switched on.

the manual is describing 2 different functions , 1 taking your foot of the brake while driving uphill holds the brake for a few seconds to assist engaging accelarator to prevent stalling this is an automatic function within the braking system and requires no activation, 2 hill hold assist requires you to hold brake for several seconds to activate that function which then will only release when throttle is applied, my old mercedes A class had the same system but you had to double tap the brake pedal in quick sucesion to activate.

 

[abmat]

Read the note. You are right that length of press depends on function. If brake only press momentarily then after a few seconds the brakes will release. Longer press then function activated and released by accelerating.

I think we’re both saying the same thing but going different ways about it b

 

[JohnM100]

You definitely have to press the brake pedal as you stop to set 'hill hold'. It then stays on until the car moves off. It doesn't time out.

What you are describing is Hold Assist which is an option and not all cars have it - hence my Q earlier about the button next to the parking brake switch on the centre console.

Hill Hold still does the green handbrake symbol on the dash but only holds for a few seconds before auto releasing.

 

[roydonaldson]

Yes, so I think what I am talking about is Hold Assist. I come up to a set of lights, stop, press the brake pedal down and the green light P light comes on in the dash in front of me. Now, on a couple of occasions, this lights has gone out and the car has had no brakes on until I rapidly put my foot back onto the brake pedal. Any ideas why that may happen ??


"Driving off with the hold assist
Applies to: vehicles with hold assist
The hold assist helps the driver if the vehicle is
stationary for a long period or very often, for in-
stance at traffic lights, on steep gradients or in
stop-and-go traffic.
Important: The driver's door must be closed and
the engine must be running.
11- To switch the hold assist on/off, press the but-
ton (@) @�page 101, Fig. 114, � ,&.. The LED
in the button will light up or go out.
11- Once it detects that the vehicle has stopped,
the hold assist keeps the vehicle stationary. In
this case, a green indicator lamp II] lights up in
the instrument cluster. You can now take your
foot off the brake pedal.
11- Drive off in the normal way: the brake will be
released automatically and the vehicle will
start moving.
In certain situations, the hold assist transfers the
job of holding the vehicle to the parking brake.
As soon as the parking brake is holding the vehi-
cle still, the warning lamp. appears in the in-
strument cluster. In addition, the LED in the(

)
button will light up."

 

[Mazman]

Yes, so I think what I am talking about is Hold Assist. I come up to a set of lights, stop, press the brake pedal down and the green light P light comes on in the dash in front of me. Now, on a couple of occasions, this lights has gone out and the car has had no brakes on until I rapidly put my foot back onto the brake pedal. Any ideas why that may happen ??


"Driving off with the hold assist
Applies to: vehicles with hold assist
The hold assist helps the driver if the vehicle is
stationary for a long period or very often, for in-
stance at traffic lights, on steep gradients or in
stop-and-go traffic.
Important: The driver's door must be closed and
the engine must be running.
11- To switch the hold assist on/off, press the but-
ton (@) @�page 101, Fig. 114, � ,&.. The LED
in the button will light up or go out.
11- Once it detects that the vehicle has stopped,
the hold assist keeps the vehicle stationary. In
this case, a green indicator lamp II] lights up in
the instrument cluster. You can now take your
foot off the brake pedal.
11- Drive off in the normal way: the brake will be
released automatically and the vehicle will
start moving.
In certain situations, the hold assist transfers the
job of holding the vehicle to the parking brake.
As soon as the parking brake is holding the vehi-
cle still, the warning lamp. appears in the in-
strument cluster. In addition, the LED in the(

)
button will light up."

Unfortunately, all I can say is that it appears there is something odd happening with your car. On my manual car, which does have hold assist, once I've braked to a stop the brake stays on as long as needed and the green 'P' stays illuminated. It releases as I drive off. Having been stuck in a traffic jam this evening, I can assure you it doesn't 'time out'.