ABS/ASR Control Unit Signal

The ABS/ASR control unit and the electronic accelerator control unit constantly exchange information. The ABS/ASR control unit sends a signal to the electronic accelerator control unit, telling it how much to reduce the throttle valve opening (due to ASR). The ASR system can reduce the throttle valve opening any amount from zero (no reduction) to total (full return to idle), depending on what is required for ASR operation. The electronic accelerator control unit sends a signal back to the ABS/ASR control unit, telling it the exact position of the accelerator actuator. The ABS/ASR control unit then decides whether its instructions for throttle valve reduction are being properly carried out. If any malfunction is detected (except during cruise control operation) the ASR system enters the safety shutdown mode. In the safety shutdown mode, the ASR warning lamp is switched on, the information exchange is halted, and no further ASR operation can occur. When turning the ignition on or when first starting the engine, the ABS/ASR control unit delays the application of wide open throttle for approx. 2 - 4 seconds. After this delay period, the electronic accelerator system operates normally. The information exchange signals consist of constant 200 Hz square wave signals, with a varying width (duty cycle or "ON" time) to convey the information. For example, the signal from Electronic Accelerator Control Unit (EACU) to ABS/ASR Control Unit varies from approx. 30% duty cycle (no throttle reduction) to approx. 5% duty cycle (maximum throttle reduction). The signal from ABS/ASR Control Unit to EACU is also a constant 200 Hz square wave with a variable duty cycle. It varies from approx. 5% duty cycle (actuator at idle position) to approx. 75% duty cycle (actuator at wide open throttle).