ESP braking moment control circuit, function - GF42.45-P-2000B

MODEL 129 with ENGINES 112, 113 with CODE (472a) Electronic Stability Program (ESP)

MODEL 202 with ENGINES 112, 113, 604 with CODE (472a) Electronic Stability Program (ESP)

MODEL 208 with ENGINES 112, 113 with CODE (472a) Electronic Stability Program (ESP)

MODEL 210 with ENGINES 111, 112, 113, 604, 605, 606, 611, 612, 613 with CODE (472a) Electronic Stability Program (ESP)

MODEL 210 / (except 210.08 /28) with CODE (472a) Electronic Stability Program (ESP)

Fig 1: Identifying ESP Braking Moment Control Circuit Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The functions of the braking moment control circuit are controlled using the components of the electric/electronic system.

The voltage for the ESP control module (N47-5) is supplied by the fuse and relay module (K40/2).

The ESP control module (N47-5) receives input signals from the following components:

4 wheel speed sensors
Steering angle sensor
Lateral acceleration sensor
Yaw rate sensor
ESP brake pressure sensor
Stop lamp switch
Parking brake switch
ME-SFI control module over CAN data line
ETC control module over CAN data line
ESP OFF switch
BAS release switch
BAS diaphragm travel sensor

The input signals are processed in the ESP control module to form output signals for the following components:

BAS solenoid valve
Solenoid valves in the hydraulic unit
High-pressure/return pump (via relays)
Stop lamp suppression relay
ME [SFI] or IFI control module via CAN data line
ETC control module over CAN data line
ESP warning lamp over CAN data line
ABS indicator lamp over CAN data line
BAS/ESP indicator lamp over CAN data line

The ESP control module (N47-5) uses the input signals to decide which of the 7 modes

Normal mode
ABS control mode
ASR control mode
EBR control mode
ESP control mode
ESP OFF mode
BAS mode
must be activated.

Normal mode

This is the case when the driving state requires no control mode. All solenoid valves in the ESP hydraulic unit (A7/3) are in the basic position, i.e. switched to the de-energized position. The system is ready for braking.

This mode also exists when there is a malfunction in the ESP, BAS or ABS system. Drive torque control is not activated.

ABS control mode

The ESP control module (N47-5) uses the wheel speed signals to detect that ABS control is required and the appropriate solenoid valves are actuated in the hydraulic unit.

The solenoid valves for the front and rear axle in the ESP hydraulic unit (A7/3) are actuated individually (4-channel control).

ASR control mode

As soon as a wheel begins to spin, the ESP control module (N47-5) actuates the high pressure and return pump (A7/3m1), the rear axle switchover solenoid valve, the rear axle charging solenoid valve and the solenoid valves for the rear axle. The solenoids for the left and right-hand side of the rear axle are actuated separately.

ESP control mode

A status controller in the ESP control module (N47-5) receives and processes the signals for the wheel speeds, the steer angle, the yaw rate of the vehicle, the lateral acceleration and the brake pressure in the front axle circuit. After evaluating the input signals, the BAS solenoid valve (A7/7y1), inlet solenoid valves, switchover valves, high pressure and return pump (A7/3m1), and the appropriate solenoid valves are actuated in order to regulate the brake pressure in the individual wheel brakes.

ESP OFF mode

If the driver presses the ESP OFF switch (S76/6) the ASR acceleration slip regulation is deactivated and the ESP stability function is also switched off when the vehicle accelerates and when rolling. The ESP stability function remains operational during braking. EBR control is deactivated.

In this switch position one brake is applied via the braking moment control circuit up to a speed of 40 km/h if one wheel spins. If activation conditions continue to exist, brake intervention continues up to max. 60 km/h. The braking torque is, however, reduced continuously.

BAS mode

The ESP control module (N47-5) uses the speed at which the driver presses the brake pedal to detect that emergency braking is required and initiates the BAS mode (refer to BAS Function).

	ABS control mode, function		GF42.45-P-3000B
	ASR control mode, function		GF42.45-P-3500B
	ESP control mode, function		GF42.45-P-3700B
	Braking Assistant (BAS), function		GF42.31-P-0001A