P42.45-2254-76
f Increased brake pressure
g Brake pedal pressure
BAS pressure increase
From the speed of the brake pedal and the vehicle speed, the ESP control module (N47-5) recognizes that the preconditions exist for activation of BAS.
At the start of the BAS control phase, the changeover solenoid valves (y24, y25) are switched to the "lock position" (closed) and the high pressure and return pump (m1) is triggered.
The suction solenoid valves (y26, y27) are opened. The self-priming high pressure and return flow pump (m1) then sucks brake fluid from the reservoir via the suction solenoid valves and the master brake cylinder.
High-pressure limitation (approx. 170 bar) is provided by the integral pressure relief valves in the changeover solenoid valves (y24, y25).
BAS is activated when the following conditions exist simultaneously:
Speed >10 km/h
+ Stop light switch operated
+ no fault is currently detected
+ the system is enabled (after self-test)
+ the activation threshold of the pedal speed has been exceeded
BAS pressure reduction
The ESP control module (N47-5) receives the Information that the emergency brake application has terminated from the ESP pressure sensors 1 and 2 (B34/1, B34/2). The high pressure and return flow pump (m1) is no longer activated, the changeover solenoid valves (y24, y25) are closed and the suction solenoid valves (y26, y27) are opened. Maximum braking power support is now switched off. The normal braking assistance force remains unchanged.
BAS is switched off when one of the following conditions exists:
The brake pedal pressure is reduced by the driver to a level at which emergency braking is no longer necessary
Stop light switch is not actuated
Speed <3 km/h
A fault is detected that causes the BAS malfunction indicator lamp to be activated
Referenced documents
- gf4245p4500b Location / task / function of ESP control module
- gf4245p4900a Location/task/function of ESP brake pressure sensor
- gf4250p4000gc Location/task/design/function of traction systems hydraulic unit