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

MODEL 219.3, 211 up to 31.5.06 except CODE (494) USA version except CODE (498) Japan version 

MODEL 219.3, 211 up to 30.6.06 with CODE (494) USA version with CODE (498) Japan version 

Fig 1: Overview Of CAN Connections

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Voltage is supplied to terminal 87 of the ESP control unit via the driver-side SAM control unit with fuse and relay module (N10/1).

The ESP control unit receives input signals from the following components:

• 4 RPM sensors (wheel speed) (via the SBC control unit)
• Steering angle sensor via CAN engine compartment
• Yaw rate and lateral acceleration sensor
• SBC control unit via CAN-SBC
• AIRmatic with ADS control unit via CAN engine compartment
• DTR control unit via CAN engine compartment
• Battery control unit (N82) via CAN interior to the central gateway control unit from there via the CAN engine compartment to the ESP control unit
• ME-SFI [ME] control unit or CDI control unit via CAN engine compartment
• ETC [EGS] control unit (AMG only) via CAN engine compartment
• Fully integrated transmission control (VGS) control unit (series production) via CAN engine compartment
• The ESP Off switch read in by the upper control panel control unit via the CAN interior to the central gateway control unit from there to the ESP control unit via the CAN engine compartment
• The parking brake indicator switch (S12) is read in discretely by the driver-side SAM control unit, from there via the CAN interior and central gateway control unit via CAN to the ESP control unit

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

• SBC control unit via CAN-SBC
• ME-SFI [ME] control unit or CDI control unit via CAN engine compartment
• Fully integrated transmission control (VGS) control unit via CAN engine compartment
• ETC [EGS] control unit (AMG only) via CAN engine compartment
• Instrument cluster via CAN engine compartment for actuation of:
  • ESP and ABS warning lamp
  • ABS indicator lamp
  • Multifunction display

On the basis of the input signals, the ESP control unit decides which of the 8 operating modes

• Normal mode
• ABS closed-loop operation (Antilock brake system (ABS))
• ASR closed-loop operation (Acceleration slip regulation (ASR))
• MSR closed-loop operation (engine braking regulation (MSR)) (see drive torque control circuit)
• ESP closed-loop operation (Electronic Stability Program (ESP))
• ESP OFF mode
• BAS operation (Brake Assist (BAS))
• DTR closed-loop operation (Distronic (DTR))

have to be engaged.

Normal operation 

This is the case when the driving state requires no control mode. The control of the normal brake application is carried out by the SBC control unit.

This operating mode exists even if a fault exists in the ESP, BAS or ABS. Drive torque control is not activated.

ABS control mode 

From the wheel speed signals the ESP control unit detects that the criteria for an ABS control exist and the appropriate solenoid valves in the traction system hydraulic unit are actuated via the SBC control unit.

The solenoid valves for the front and rear axle are actuated individually (4-channel control).

ASR control mode 

As soon as a drive wheel tends to spin, the ESP control unit actuates the appropriate solenoid valves of the rear axle in the traction system hydraulic unit via the SBC control unit.

ESP control mode 

In the ESP control unit the signals of the wheel speeds, steering angle, the rotational speed of the vehicle, the lateral acceleration of the vehicle as well as the brake pressures of the individual wheels are recorded and processed by a drive status regulator. After evaluating the input signals the required solenoid valves are actuated via the SBC control unit in order to regulate the brake pressure in the individual wheel brakes.

ESP-Off-operation (ESP OFF) 

When the ESP OFF switch is operated the ESP drive moment control is switched off and the ESP stability function is canceled when accelerating, rolling and in overrun mode. Only the ESP stability function continues to be retained when braking. The MSR control is switched off.

In this switch position an intervention in the brake system takes place via the braking torque control circuit up to 40 km/h when one drive wheel is spinning. If cut-in conditions continue to be present, the intervention in the brake system is retained up to a maximum of 60 km/h. However the braking torque is continuously reduced.

Exhaust emission test/rolling mode 

For vehicle test purposes the ESP can be set in the "exhaust gas test" mode if via the instrument cluster the corresponding workshop menu is activated and then the engine is started. ESP, ASR and MSR are then switched passive and the ESP and ABS warning lamp and ABS indicator lamp light up in the instrument cluster.

In addition, a message is displayed in the multifunction display of the instrument cluster. The wheel speeds of the driven axle are reflected on the wheels of the non-driven axle.

BAS mode 

From the speed of the brake pedal the ESP control unit detects via the SBC pedal value sensor that an emergency case braking exists and introduces the BAS mode (see BAS function).

Distronic closed-loop operation 

The DTR control unit sends the signals for a DTR control to the ESP control unit. The requests are prioritized there and passed on to the ME-SFI [ME] control unit (gasoline injection engine) or to the CDI control unit (diesel engine) for drive torque reduction. An intervention in the brake system is carried out if necessary. The display function and warning function of the DTR is passed on direct from the DTR control unit to the corresponding recipients.