Acceleration slip regulation (ASR) To achieve optimum traction if the drive torque is too high (wheel spinning) acceleration slip regulation is required. Control of torque reduction is achieved by data transfer between the control module of the built-in ASR (acceleration slip regulation) traction control system (N47-1) or ESP (N47-5) and the corresponding control module for the injection and ignition system via the CAN databus. With gasoline engines these control modules are: EFP (N4/1), LH (N3/1, N3/2, N3/3), HFM (N3/4) or ME (N3/10, N3/11, N3/12) and with diesel engines the control modules are ERE (N3/7), EVE (N3/8) or CDI (N3/9). Four cylinder gasoline engine with supercharger, 6, 8, and 12 cylinder gasoline engines: Control module EFP (N4/1) or ME (N3/10, N3/11, N3/12) reduces the throttle valve position on the throttle valve positioner (M16/1 or M16/6) with respect to the accelerator pedal position set by the driver and/or retards the ignition timing from the HFM control module (N3/4), ME (N3/10, N3/11, N3/12) or ignition control unit (N3/1).

Four cylinder gasoline engine without supercharger: The fuel feed is switched off by the HFM control module (N3/4). Diesel engine: The quantity of fuel is reduced by the ERE control module (N3/7), EVE (N3/8) or CDI (N3/9). A continuous check takes place in the ASR or ESP control module (N47-1 or N47-5) whether, e.g. because of suddenly improved road adhesion, the control function can be canceled so as to permit the drive torque desired by the driver via the accelerator pedal as soon as possible.

MSR engine friction torque control (not with 4 cylinder gasoline engine without supercharger) If slip occurs on the drive wheels when the accelerator position is reduced, this is detected by the ASR or ESP control module (N47-1 or N47-5). Four cylinder gasoline engine with supercharger, 6, 8, and 12 cylinder gasoline engines: The signal (raising of throttle valve) is transmitted to the EFP or ME control module (N4/1) (N3/10, N3/11, N3/12) via the CAN databus. The calculated throttle valve opening is controlled by the control module (N4/1, N3/10, N3/11, N3/12) via the throttle valve positioner (M16/1).

Diesel engine: The signal (increase fuel quantity) is transmitted via the CAN databus to the ERE (N3/7), EVE (N3/8) or CDI (N3/9) control module. The fuel quantity injected is increased by the control module. With this information, the drive torque can be changed so that no slip occurs at the drive wheels. This improves the lateral stability of the vehicle. This process occurs without driver information (warning lamp A1e21 or A1e41).

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

The ABS and ASR functions are included in the ESP electronics of the brake control circuit. The Brake Assist (BAS) function is also included on model 168 and on vehicles with engine 112, 113 (model 210 also engine 606, 611). The ABS and ASR basic components are also combined in the traction systems hydraulic unit. The functions for the electronic accelerator (EA) and cruise control system (Tempomat) are included in the engine control module. Via a CAN data bus data can be exchanged between the ESP control module and the engine control module and, if necessary, with the transmission control module and BAS control module. Advantages Improves the starting off and acceleration capacity due to increased traction; particularly beneficial on road surfaces with different levels of adhesion and when cornering. Increases active dynamic safety, since only a wheel which is not skidding can provide optimum propulsion without any loss of lateral control.

Automatically adapts the engine torque to the ability of the wheels to transmit this to the road when the driver applies too much throttle. Reduces the risk of skidding under all road conditions by automatic stabilization when braking, accelerating or rolling away evenly. Significantly improves the directional stability of the vehicle when cornering - up to the limit range. Reduces the stopping distance at corners or on roads with a slippery surface. A flashing warning lamp in the speedometer signals ESP control mode to the driver and informs him that he has approached the physical limit with his vehicle. ESP or ASR can be shut off using the ESP OFF switch (ASR OFF, on model 168) which is recognized by the warning lamp in the speedometer illuminating permanently. Better traction (milling effect) can therefore be achieved in deep snow or when snow chains are fitted.

Example A: Understeering vehicle (cornering left) The vehicle pushes outwards over the front wheels. A precisely calculated braking action is performed on the left rear wheel. Example B: Oversteering vehicle (cornering left) The tail of the vehicle breaks away. A precisely calculated braking action is performed on the right front wheel. a Desired travel direction b Braked wheel c Corrective moment produced in vehicle d Understeering vehicle motion e Oversteering vehicle motion
		P42.45-0203-02		P42.45-0204-02

ESP controls: when cornering (vehicle oversteers or understeers) when driving straight ahead (vehicle deviates off course due to uneven road conditions) To be able to perform these extremely precise control interventions, an expanded system of sensors is required compared with ASR. A distinction is made between: 1.) Sensors which recognize the driver requirement Steering angle sensor Accelerator pedal position (throttle valve actuator) 2.) Sensors which measure the actual vehicle characteristics ESP yaw rate sensor Lateral acceleration sensor ESP brake pressure sensor Wheel speed sensor The wheel speeds, steering angle, yaw rate of vehicle, lateral acceleration and brake pressures on the front axle are recorded and processed in the ESP control module (N47-5). The ESP control module (N47-5) is connected to the control modules of the engine transmission management system via a CAN data bus. This digital line connection enables rapid exchange

of data between the ESP, ME-SFI and ETC control modules. The ESP, SPS and BAS control module (N47-5) is continuously supplied with current data on engine torque, accelerator pedal position and transmission ratio. The forces which want to turn the vehicle about the center of gravity are recognized via the turn rate and lateral acceleration sensor. The longitudinal and lateral forces at the wheels can be calculated by means of the value acquisition which is carried out. If these values exceed certain control thresholds, the appropriate solenoid valves and the high pressure and return pump in the hydraulic unit are actuated via the ESP, SPS and BAS control module (N47-5) in order to control a defined brake pressure selectively at one or several wheels. At the same time commands are passed on to the ME-SFI and ETC control modules via the CAN data bus. To reduce the drive moment, calculated values for throttle valve position and ignition timing are specified and a downshift prevented if necessary. The precise and accurately proportioned intervention is completed within a few fractions of a second. Active brake intervention and drive moment reduction by the ESP ensure optimum vehicle stability.

	Notes on towing		AH42.00-P-0001-05B
	Notes on testing electronic components and systems for damage		AH42.00-P-0001-06B
	Electronic stability program (ESP), location of electrical components	Model 129 with engines 104, 119, 120	GF42.45-P-0001-03A
		Model 140	GF42.45-P-0001-03B
		Model 210 with engine 119	GF42.45-P-0001-03C
	Electronic stability program (ESP), driver information		GF42.45-P-0001-04A
	Electronic stability program (ESP), location of hydraulic components	Model 129 with engines 104, 119, 120	GF42.45-P-0001-02A
		Model 140 Model 210 with engine 119	GF42.45-P-0001-02B
	ESP brake moment control circuit, function		GF42.45-P-2000A
	ASR drive moment control circuit, function		GF42.40-P-2100A

GF42.45-P-0001-02A

Electronic stability program (ESP), location of hydraulic components

Model 129 with engines 104, 119, 120

P42.45-0248-09

GF42.45-P-0001-03A

Electronic stability program (ESP), location of electrical components

Model 129 with engines 104, 119, 120

P42.45-0249-09