Function of ASR V control module - GF42.40-P-4500-01A

The ASR control module (N47-1) is divided up functionally as follows:

• Signal conditioning
• Logic section
• Safety circuit
• Additional functions

Signal conditioning 

The following input signals are conditioned for the logic section:

• 4 speed sensors
• Stop lamp switch (S9/1)
• Throttle valve requirement value (except diesel or gasoline engine with fuel shut-off)
• ASR OFF switch (S76/5)
• Parking brake switch (S12)

Logic section 

The conditioned input signals are processed in the logic section and converted into output signals.

Speed signals

The conditioned speed signals are constantly compared with each other and then with specified slip thresholds (differential speeds between the front and rear wheels, depending on vehicle speed).

The following values are determined by this comparison process:

• Drive slip
  • Acceleration
  • Front wheel speed
  • Corner recognition
  • EBR overrun slip (except gasoline engine with fuel shut-off)

If the values determined exceed the specified slip thresholds, an ASR control mode is introduced.

Stop lamp switch signal:

When the brake is operated, a signal is transmitted to the logic section and the ASR control mode is terminated immediately. However, EBR control can continue.

Throttle valve requirement value signal: (except diesel engine or gasoline engine with fuel shut-off)

In ASR control mode the logic section carries out a specified/actual value comparison of the throttle valve position.

ASR OFF switch (S76/5) signal:

The drive moment control circuit is switched off and the ASR warning lamp is actuated if there is a signal from the ASR OFF switch.

Parking brake switch (S12) signal:

No EBR control mode is permitted if there is a signal from the parking brake switch.

Safety circuit 

The task of the safety circuit is to recognize faulty signals in the control module and fault in the electrical cable system. The actuation of the solenoid valves and the high-pressure/return pump is monitored during the control process. If a fault is recognized, the system is switched off and this is indicated to the driver by the ASR MIL (A1e22) or BAS/ASR (A1e48) malfunction indicator lamp and/or ABS MIL (A1e17) coming on. In addition a fault code is stored in the control module.

The safety circuit also continuously monitors battery voltage. If the battery voltage is less than 10.5 V, the system is also switched off until the voltage is in the specified range again.

Additional functions 

Partial function of speed-sensitive power steering (models 140, 210) 

The control module calculates the specified current for actuating the SPS P-valve (y10) from the vehicle speed which is available internally and the status signal.

Wheel speed and speed status signal outputs 

• Wheel speed output: The ASR control module supplies the current wheel speed of each wheel for systems which need a wheel speed signal.
• Speed status signal output: The ASR control module supplies the speed status signal for systems which need information on the current drive condition (vehicle stationary, vehicle driving, speed sensor defective).

Indicator lamp actuation 

The signals from the brake pad wear contacts and the parking brake are recorded as of control module version LK55/1. They are transmitted to the instrument cluster via a serial data bus together with the signals for the ABS and ASR MIL and warning lamps and on vehicles with CAN connection on the instrument cluster via a CAN data bus.