GF42.45-P-4500-01E Function of ESP control module

GF42.45-P-4500-01E Function of ESP control module
- with CODE (472) Electronic Stability Program (ESP)

Function of ESP control module:

The ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N475) (model 163) is divided up functionally as follows:
^ Signal conditioning
^ Function logic component
^ Safety circuit
^ Additional functions

Signal conditioning
The following input signals are processed by the function logic component for calculations or as information:
^ Calculation of vehicle speed/slip signals of the 4 rpm sensors
^ Calculation of lateral forces
Steering angle sensor signal (N49) via. engine compartment (CAN-C)
ESP lateral acceleration sensor signal (B24/2)
(models 203, 209), lateral acceleration sensor (B43) (model 163)
ESP yaw rate sensor signal (N64)
(models 203, 209), (B45) on (model 163)
BAS diaphragm travel sensor signal (A7/7b1)
^ Calculation of longitudinal forces
CAN data on engine torque:
CAN-Info current transmission gear
ESP brake pressure sensor signal(B34) (models 203, 209),
ESP brake pressure sensor 1 (B34/1) and ESP brake pressure sensor 2 (B34/2) (model 163)
^ Information signals (operation)
ESP brake pressure sensor signal(B34) (models 203, 209),
ESP brake pressure sensor 1 (B34/1) and ESP brake pressure sensor 2 (B34/2) (model 163)

Parking brake indicator switch signal (S12) via engine compartment CAN (CAN-C)
ESP OFF switch signal (N72/1 (s1) (models 203, 209), (S76/6) (model 163)
BAS release switch signal (A7/7s1)
BAS diaphragm travel sensor signal (A7/7b1)

Function logic component
The conditioned input signals are processed in the logic section and converted into output signals. The conditioned 4 wheel rpm signals are constantly compared with each other and with specified engagement limits at the front and rear axle depending on the vehicle speed.

The following values and controlled variables are determined:
^ Vehicle speed
^ Acceleration/deceleration
^ Wheel slip (ABS)
^ Drive slip (ASR)
^ Decel slip (MSR)

Steering angle sensor sensor (N49)
These two detection values in conjunction with the vehicle speed provide the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163) with a record about the vehicle behavior desired by the driver.

ESP lateral acceleration sensor signal (B24/2)
(models 203, 209), lateral acceleration sensor (B43) (model 163) From the sensor signal, the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (models 163) determines the lateral forces occurring when cornering. The driving condition controller in the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163) detects an oversteering vehicle from the lateral acceleration sensor signal together with yaw rate signal.

The change in the direction of travel or cornering is detected via the steering angle sensor signal and the different wheel rpm of the front wheels.

ESP yaw rate sensor signal (N64) (model 203, 209), (B45) on (model 163)
Through the sensor in the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (models 163) the movements (yaw rate) which want to rotate the vehicle about its vertical axis, as occur when a vehicle skids. Using the signals from the ESP lateral acceleration sensor (B24/2) (models 203, 209), lateral acceleration sensor (B43) (model 163) and yaw rate sensor ESP (N64) (models 203, 209), (B45) on (model 163) the ESP and BAS control unit (N47-5) (model 203, 209), ESP control unit (N47-5) (model 163) detects the actual handling of the vehicle.

CAN data on engine torque
Via the engine compartment CAN (CAN-C) the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163), motor electronics control unit (N3/10) or CDI control unit (N3/9) is informed about the engine torque delivered. In ESP control mode the function logic component requests the engine control module to set a reduced engine torque.

CAN data on currently engaged gear (automatic transmission only) Via the engine compartment CAN (CAN-C) the function logic section (ESP) is constantly informed by the ETC [EGS] control unit (N1 5/3) about the current gear. The current gear is used to calculate the drive forces acting on the drive wheels and for drive torque control.

ESP OFF switch signal (N72/1s1) (model 203, 209), (S76/6) (model 163) If a signal from the switch is applied, the drive torque control circuit is switched off and the ESP warning lamp (A1 e41). (models 203, 209), ETS warning light (A1 e36) (model 163) is actuated permanently.

Brake pressure sensor signal (B34) (models 203, 209), ESP brake pressure sensor 1 (B34/1) and ESP brake pressure sensor 2 (B34/2) (model 163)
The brake pressure is recorded with the sensor and used by the logic section to calculate the wheel brake forces (longitudinal forces). Actuation of the brake is also registered by the driver.

If an ESP control is necessary, the existing wheel brake forces (longitudinal forces) are also included for calculating the lateral stability (lateral forces)

Parking brake indicator switch signal (S12)
If there is a signal from this switch, no MSR closed loop operation is permissible

BAS diaphragm travel sensor signal (A7/7b1)
Using this the brake pedal speed is calculated which is needed for the use of BAS.

Safety circuit
The safety circuit detects faulty signals from sensors, faults in the control module and in the electric line system. The actuation of the high-pressure and return flow pump (A7/3m1), is monitored during this control process. The solenoid valves are monitored permanently.

If a fault is detected, the system is switched off and this is displayed to the driver by the multifunction display (except model 163) (A1 (p1) 3) In addition, a fault code is stored in the control module. The safety circuit also constantly monitors the battery voltage. If the voltage drops below 10.5 V or rises above 17.5 V, the system is again shut down until the voltage returns to the specified range.

Speed-sensitive power steering subfunction (SPS)
The control unit calculates the specified current for actuating the SPS [PML} solenoid valve from the internal vehicle speed and the status signal (Y10).

Brake Assist (BAS) sub-function
The conditioned input signals are processed in the logic section and a Brake Assist brake application introduced if necessary.

Wheel speeds and speed status signal outputs
Output of wheel rpm
For systems which require a wheel speed signal the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163) provides the current wheel rpm from each wheel.

Output of rpm status signal
For systems which require information on the current vehicle status (vehicle stationary, vehicle moving, rpm sensor defective), the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163) provides the rpm status signal.

Indicator lamp actuation
The signals from the parking brake and brake lining wear contacts are recorded by the ESP and BAS control unit (N47-5) (models 203, 209), ESP control unit (N47-5) (model 163). Together with the signals for the multifunction display (except model 163) (A1p13), the ABS indicator lamp (A1e17) and ESP warning lamp (A1 e41). (models 203, 209), ETS warning light (A1 e36) (model 163) they are passed on to the instrument cluster (A1) via the engine compartment CAN (CAN C).