ESP brake moment control circuit, function - GF42.45-P-2000A

MODEL 140 with CODE (472a) Electronic Stability Program (ESP)

MODEL 129 with ENGINE 104, 119, 120 with CODE (472a) Electronic Stability Program (ESP)

MODEL 210 with ENGINE 119 with CODE (472a) Electronic Stability Program (ESP)

Fig 1: Identifying ESP Brake Moment Control Circuit Function Flow Chart

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The corresponding functions of the brake moment control circuit are controlled by the electrical/electronic control components.

The voltage is supplied to the ESP control module (N47/5) on models 129 and 140 via the base module (N16/1), and on model 210 via the relay unit (K40).

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

4 wheel speed sensors
Steering angle sensor
Lateral acceleration sensor
Yaw sensor
ESP brake pressure sensor
Stop lamp switch
Parking brake switch
ME control module via CAN data line
EGS control module via CAN data line
ESP OFF switch

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

Charging pump
Solenoid valves
High-pressure pump/return pump (via relay)
ME control module via CAN data line
EGS control module via CAN data line
ESP warning lamp (serial or via CAN data bus)
ABS indicator lamp (serial or via CAN data bus)
ESP indicator lamp (serial or via CAN data bus)

The ESP control module (N47-5) decides which of the 6 operating modes are to be switched based on the input signals

Normal mode
ABS control mode
ASR control mode
MSR control mode
ESP control mode
ESP off mode

Normal mode

In this case there is no vehicle condition which requires a control mode. All solenoid valves in the ESP hydraulic unit (A7/3) are switched to the normal position, i.e. de-energized. The system is ready for braking.

This operating mode exists even if there is a fault in the ESP or ABS. Drive moment control is not activated.

ABS control mode

From the wheel speed signals, the ESP control module (N47-5) recognizes that the criteria for an ABS control exist and the appropriate solenoid valves in the hydraulic unit are actuated.

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 drive wheel tends to spin, the ESP control module (N47-5) actuates the charging pump (M15), the high-pressure pump/ return pump (A7/3m1), the rear axle switchover solenoid valve, the rear (N47-5) actuates the charging pump (M15), the high-pressure pump/ return pump (A7/3m1), the rear axle switchover solenoid valve, the rear axle pressurizing solenoid valve and the solenoid valves for the rear axle. The solenoid valves for the left or right rear axle are actuated separately.

ASR control mode is interrupted via the stop lamp switch when the brake pedal is operated.

ESP control mode

The signals of wheel speeds, steering angle, yaw of the vehicle, lateral acceleration as well as the brake pressure of the front axle circuit are recorded and processed by a vehicle condition controller in the ESP control module (N47-5). After evaluating the input signals, the charging pump (M15), pressurizing solenoid valves, switchover valves, high-pressure pump/return pump (A7/3m1) as well as the required solenoid valves are actuated in order to control the brake pressure in the individual wheel brakes.

ESP off mode (ESP OFF)

When the ESP OFF switch (S76/6) is operated the ASR drive moment control is switched off and the ESP stability function is therefore cancelled. The EBR control remains active but is switched to a less sensitive mode.

In this switch position a brake intervention occurs for one spinning drive wheel via the brake moment control circuit. If engaging conditions continue to exist, brake intervention is retained up to max. 60 km/h. However the brake torque is progressively reduced.

	ABS control mode, function		GF42.45-P-3000A
	ASR control mode, function		GF42.45-P-3500A
	ESP control mode, function		GF42.45-P-3700A