W/ ASR

Electronic Accelerator Control System Diagram:

NOTE: Vehicles equipped with ABS/ASR use an electronic accelerator control module.

PURPOSE
The electronic accelerator control module (N4/1) controls the cruise control, idle speed functions and electronic engine control for ABS/ASR to insure smooth and consistent operation regardless of engine temperature and load.

OPERATION
When the ignition switch is in the ON position, the idle speed control function is in operation. The position of the throttle valve for idle speed and ABS/ASR is determined by the control module via the nominal value potentiometer (accelerator pedal input) in the electronic accelerator actuator (M16/1). The actual value potentiometer in the electronic accelerator actuator signals the position of the throttle valve. The electronic accelerator control module compares the signals and specifies the position of the throttle valve via the output signal. This signal is used by the electronic accelerator actuator to adjust the throttle valve.

Before starting the engine, the throttle valve position is determined by the engine temperature. Once the engine is running, the idle speed and ABS/ASR are controlled by the electronic accelerator control module which provides a constant idle RPM and limits the maximum torque output to the drive wheels. For torque output regulation (ABS/ASR), the control module uses the input signal from the ABS/ASR control module.

Idle speed control function
The idle speed control function uses the following information to determine the correct idle speed:
^ Engine speed (TN-signal)
^ Coolant temperature
^ Vehicle speed signal
^ Selector lever position
^ A/C compressor engagement signal

Idle Speed/Temperature Chart:

During idle, the control module keeps the engine speed at a constant RPM depending on engine coolant temperature.

Electronic Accelerator System Schematic:

Warm-up Control Function
The warm-up control is effective at all engine temperatures. After each start-up (accelerator pedal in idle position) the engine increases the idle speed for approx 20 seconds. Below 20 °C (68 °F) the engine speed is 900 - 1000 RPM.

A/C engagement Control Function
When the A/C compressor is turned on, the throttle valve opening is increased before the A/C compressor engages. This keeps the engine idle speed at a nearly constant RPM.