GF42.31-P-2000A BAS brake application, function
GF42.31-P-2000A BAS brake application, function
The functions of the BAS brake booster (A7/7) are controlled using the components of the electric/electronic system.
In model 168, the voltage supply for the BAS control unit (N48) is via the fuse and relay box (F1). In models 129 and 140 via the base module (N16/1). In models 163, 170, 202, 208, 210, 215, 220 via the relay module (K40). In models 203 and 209 via the SAM control unit (N10/1).
In all vehicles with engines 112, 113, 605, 606, 611, 612, 613 and ESP, the BAS control unit function is integrated in the ESP control unit (N47-5).
In models 163, 168, 203, 209, 215, 220 the BAS control unit function is integrated in the ESP control unit (N47-5).
The BAS control unit receives input signals from the following components:
^ ME control unit (via CAN data line)
^ Traction system control unit (via CAN data line)
^ BAS diaphragm travel sensor
^ BAS release switch
In the BAS control unit, the input signals are converted into output signals for the following components:
^ BAS solenoid valve
^ BAS/ESP indicator lamp (via CAN data line)
On the basis of the input signals, the BAS (N48) or ESP (N47-5) control unit decides which of the 3 operating modes
^ Normal mode
^ BAS pressure increase
^ BAS pressure reduction
is to be activated.
Normal operation
In this case, the brake application is not at the higher pedal speed (that requires activation of BAS). The solenoid valve in the BAS brake booster (A7/7) is de-energized in the basic position.
The system is ready for braking.
Service brake and ABS function normally.
This mode is also set if there is a fault in the BAS.
BAS pressure increase
From the speed of the brake pedal, the BAS control unit (N48) recognizes that the preconditions exist for activation of BAS. The BAS solenoid valve (A7/7y1) is activated by the BAS control unit (N48) and the brake booster produces the maximum brake assistance power.
BAS is activated when the following conditions exist simultaneously:
^ Speed > 8 km/h
+ BAS release switch is actuated
+ no current fault is detected.
+ the system is enabled (after self-test)
+ Pedal speed activation threshold exceeded
BAS pressure reduction
The BAS control unit (N48) receives information from the BAS release switch (A7/7s1) that the emergency brake application has terminated. The BAS solenoid valve (A7/7y1) is no longer activated and the maximum braking assistance force is switched off. The normal brake servo assistance remains unchanged.
BAS is switched off when one of the following conditions exists:
^ BAS release switch is not actuated
^ Speed < 3 km/h
^ Duration of activation > 20 s
^ If no signal from the stop light switch is present after activation of BAS
^ A fault is detected that causes the BAS indicator lamp to be activated
