All the cars in my past have had emergency brakes. Foot or hand operated, with a cable that went to a brake. Now here I have a little lever switch on the console which I pull up and I can feel my brake pedal depress a little farther, but I have no idea what I have accomplished.
Has anyone tried the emergency (parking )_ brake while the car is in motion? If your brake pedal goes dead and you need braking, will this little switch on the console achieve anything for you?
I am reluctant to experiment.
Thanks,
P.

 

I was rolling slightly when I pulled up on the switch and the car made a grinding noise and stopped immediately. Haven't tried it at speed and I'm curious too. I'm guessing it would activate the parking brake completely at any speed. Anyone know?

 

Whilst most people will only use this brake in an emergency, it is applied every time the engine is stopped, the transmission put in park and the ignition key removed. Clearly this done to keep the mechanism exercised. If you pull on the lever, the brake will be applied electrically and is quite powerful although obviously not as powerful as the regular brake and it only applies on the rear wheels anyway. You release the brake by pushing down on the lever.

 

Dynamic Apply

While the vehicle is moving, the dynamic apply mode gives emergency braking. At a vehicle speed greater than 3 km/h 2 mph), operating and holding the EPB switch up produces a gradual deceleration of the vehicle. The red EPB warning indicator illuminates, together with a warning in the message center and a warning chime. The vehicle stop lamps also illuminate, activated by a CAN Bus message from the ABS control module to the BCM/GWM (Body Control Module / Gateway Control Module). The dynamic apply operation is cancelled if the EPB switch is either released to its neutral position or operated down to the release position, or when the accelerator pedal is operated.

There are three modes of dynamic apply, which the ABS control module uses in the following order of preference:

1. Hydraulic Dynamic Brake Function (HDBF)
2. Degraded Dynamic Brake Function (DDBF)
3. Actuator Dynamic Brake Function (ADBF)

The HDBF and DDBF modes use hydraulic braking on all four wheels to decelerate the vehicle. The ADBF mode uses the EPB actuators to operate the rear brakes to decelerate the vehicle.

Hydraulic Dynamic Brake Function (HDBF)

The ABS control module controls the braking operation. The ABS control module monitors the deceleration rate using the wheel speed sensor signals, and it adjusts the hydraulic pressure to the brakes as necessary to achieve the required deceleration. All of the anti-lock control - traction control system brake modes stay enabled.

Degraded Dynamic Brake Function (DDBF)

The braking operation is controlled by the ABS control module. The ABS control module monitors the deceleration rate using the wheel speed sensor signals if available, and it adjusts the hydraulic pressure to the brakes as necessary to achieve the required deceleration. This mode will work with a maximum of two failed wheel speed sensors.

Actuator Dynamic Brake Function (ADBF)

The ADBF mode is used if the ABS control module cannot operate the brakes hydraulically, but still has wheel speeds available. The wheel speed inputs allow the ABS control module to adjust the clamp load on the rear brakes as necessary to produce maximum deceleration without locking the wheels. When the vehicle speed decreases to 3 km/h (2 mph), the ABS control module fully applies the EPB.

ADBF uses the EPB actuators to apply the rear brakes only, there is no hydraulic brake application and the front brakes are not applied.

 

Thanks for that write up. I knew I didn't know how it worked and now I know why.
There is still an element of blind faith in the system.
P.

 

Wow, complicated process but it makes sense. Yes, thanks for the explanation. Where did you get it?

 

TOPIx

 

Emergency brakes are really a parking brake that in the event of an emergency will stop the car.

It is not recommended to use whilst the car is moving unless in an emergency.

Do not even "test it" .............

There are three types of parking brake

The type fitted to many top end cars is operated electronically, when the lever is operated the rear brakes come on fully.......and will stop the car.As you can imagine this is something you only want to do if you have to.And if you were doing over 25 mph I would have the rear brakes checked by a mechanic asap.Electronic parking brakes tend to operate automatically as well, put car in P , on comes the parking brake. Take it out of P, chocks away.You don't need to worry about it.Untill it goes wrong, the electronic bit of electronic parking brake can have a brain fart every now and then........and electronic parking brakes which stick on........are a bitch to fix or release when stuck on the side of the road in the middle of nowhere at night, and its probably gonna rain as well.

The second type is where the brake is applied by pushing a foot pedal , and then released by either pushing the foot pedal again or pulling a little lever. This type also comes on fully and once its on its a bitch to get off. So this type is also a use it only if you need it.........I drove an Explorer 40 odd miles with no brakes relying on the foot pedal operated brake to slow the car. NY rush hour traffic didn't help but I took it easy and made it home. I would not recommend doing that for long, I feathered my car home and it tore the rear calipers up.

The third type is my fave.......a handle between the seats is pulled up, which pulls on a cable which operates the rear brakes, apart from being simple you can control the braking force applied to the rear brakes. So in an emergency you could quite confidently get home.......in an emergency, and to control hand brake turns......you can yank the handle up hard, which one would do in an emergency.......and the car will stop.

Do not operate that lever if you are driving........unless you have to.