GF42.47-P-2000SX Additional Functions, Adaptive Brake (ABR), Function
GF42.47-P-2000SX Additional functions, adaptive brake (ABR), function
The following additional functions are integrated in the Adaptive Brake (ABR) and are coordinated by the ESP control unit (N47-5):
^ HOLD
^ Precharging
^ Dry braking
^ Hill start assist
^ Failed boost function (on engine 275)
^ Fading brake support
^ Air gap reduction (Air gap)
^ Standstill coordinator
^ Trailer stabilization
Additional function
HOLD
HOLD makes life easier for the driver optionally:
^ When starting off uphill
^ When maneuvering on mountain roads
^ When waiting in traffic
With and the additional HOLD function is deactivated by coding in the ESP control unit. This takes place by the coding information of the central gateway control unit (N93).
Function description of HOLD
When the vehicle is at a standstill HOLD can be switched on by actuating the brake pedal. The actuation of the brake pedal is detected via the BAS diaphragm travel sensor (A7/7b1). The vehicle is then held in position without any further actuation of the brake pedal. The braking effect is canceled when starting off by pressing the accelerator, via the accelerator pedal sensor (B37).
Switching on HOLD
HOLD can be switched on when
^ the vehicle is stationary
^ the electronic parking brake is not closed
^ the trunk lid is closed with DIRECT SELECT gear selector switch (S16/13) in position "R"
^ always when the seat belt is worn or the transmission is shifted out of position "P" when the driver door is closed
^ the engine hood is closed
^ the engine be running
^ the gear selector switch is not in position "P"
^ Histrionic Plus (with code (233) Histrionic Plus) is not active
Actuate the brake pedal, then depress the brake pedal briskly again until the message "HOLD" appears in the multifunction display (A1p13). The vehicle is held automatically when the brake pedal is released afterwards.
Switching off HOLD
HOLD is switched off automatically when
^ the accelerator pedal sensor (B37) is actuated
^ the gear selector switch is switched into position "P"
^ the brake pedal is actuated again until the display "HOLD" disappears in the multifunction display
^ the parking brake is actuated via the electric parking brake switch (S76/15)
^ Histrionic Plus (with code (233) Histrionic Plus) is activated
Driver status
A belt tongue inserted into the seat belt buckle or shifting out of position "P" when the driver door is closed is interpreted as the presence of the driver. When the driver door is open and a belt tongue is not inserted into the seat belt buckle the driver status is not clear and the driver is thus presumed absent. HOLD is not activated when the driver status is not clear.
The status of the seat belt buckle is detected by the restraint systems control unit (N2/7) and the driver seat belt buckle and seat belt warning switch (S68/1).The opening of the driver door on model 216 is detected by the left door control unit (N69/1) and the left rotary tumbler switch (A85s1) and in model 221 by the left front door control unit and the left front rotary tumbler switch (A85s1).
Additional function
Precharging
The function is permanently active and assists the performance of the brake system by already applying the brake linings (precharging) when the accelerator pedal sensor is released. As a result the response time of the brake is reduced and the stopping distance reduced during emergency stops.
Function description of precharging
To reduce the response time during panic braking the air gap of the wheel brake system is already overcome when the accelerator pedal sensor is overcome and the brake linings are applied.
If the driver subsequently depresses the brake pedal, a spontaneous braking effect is achieved and thus the stopping distance is reduced. In the process the release gradient of the accelerator pedal sensor is used to detect the rapid braking requirement. The precharging process is terminated after a short time if the driver does not apply the brake.
Determination of the triggering threshold for precharging
If the boundary conditions are met, the associated release gradient is determined each time the accelerator pedal sensor is released completely. The triggering threshold depends on the pedal travel. With small pedal travels before the pedal is released a smaller pedal release gradient is needed in order to activate precharging, than with large pedal travels before the pedal is released.
Precharging is not active when:
^ ESP faults are present
^ Control intervention functions take place through ABS, ESP or ASR
^ Faults are present in the engine control
^ CAN faults are present
Additional function
Dry braking
The function is permanently active and assists the performance of the brake system in the wet. The response time of the brake is reduced by cyclical dry braking of the brake disks.
Function description of dry braking
Dry braking is activated as soon as the windshield wiper leaves its basic position. Dry braking itself is only carried out at the front axle for a few seconds with a very small brake pressure (< 1 bar).
Hill start assist
In the case of starting off uphill (longitudinal gradient) when changing from the brake to the accelerator pedal sensor a delayed depressurization is carried out in the brake system in order to prevent the vehicle rolling back unintentionally.
A longitudinal gradient is detected by the ESP control unit via the turn rate, lateral and longitudinal acceleration sensor (B24/15)
Hill start assist is not active when
^ the vehicle is driven on the level or downhill
^ the transmission is in position "N"
^ the parking brake is actuated
^ ESP faults are present
Additional function
Failed boost function
In combination with signals from the BAS travel differential sensor (A7/7b2) (only with engine 275) the failed boot function serves to ensure a sufficiently high brake pressure level in the system in the event of a shortage of brake boost through the BAS brake booster (A7/7).
Function description of failed boost function
If during a brake application by the driver it is detected by the BAS travel differential sensor and the ESP control unit that the BAS brake booster does not provide adequate driver assistance, then failed boost ensures driver assistance by hydraulic brake boost.
Additional function
Fading brake support
The fading brake support function serves to provide additional driver assistance when the brake system is hot in order to achieve the best possible deceleration in this operating case as well. In the event of a particularly severe heating up an information message is shown in the multifunction display of the instrument cluster (A1).
Function description of fading brake support
Heating up is determined based on a temperature model of the brake disk. If a particular threshold is exceeded fading is assumed, fading brake support becomes active. In addition this function can also be activated by the comparison of the brake pressure level with the actual deceleration or by the direct request through the antilock brake system (ABS).
Additional function
Air gap reduction (Air gap)
Air gap reduces the air gap between the brake disk and lining in order to speed up any subsequent brake applications through ASR or ESP.
Additional function
Standstill coordinator
When the support systems are active when the vehicle is stationary the standstill coordinator promotes the actuation of the electric parking brake (EFB) or shifting into position "P" by the Intelligent servo module for DIRECT SELECT (A80). This changes over the vehicle into a secured condition.
The following event lead to actuation of the electric parking brake controller unit (A13):
^ Engine hood open
^ Trunk lid open and reverse gear engaged
The following events lead to actuation of the EFB and the Intelligent servo module for DIRECT SELECT:
^ Faults in a security system or the ESP control unit
^ ABR overload protection system
^ Driver presence unclear
^ Critical condition of on-board electrical system
^ Engine OFF
Additional function
Trailer stabilization
Trailer stabilization reduces vehicle combination swinging by specific brake interventions in order to stabilize the vehicle and trailer.
