Vehicle Speed Sensor (Sienna)

Wheel speed sensors on each wheel deliver an input signal to Anti-Lock Brake System (ABS) Electronic Control Unit (ECU). ABS ECU converts input signals from wheel speed sensors to a 4-pulse input signal to the instrument cluster. Instrument cluster then converts 4-pulse input signal to a rectangular waveform and then sends input signal to Engine Control Module (ECM). ECM determines vehicle speed by using input signal. ECM may use input signal for controlling fuel injection system, electronically controlled automatic transaxle and various other systems. On models with Vehicle Skid Control (VSC), ABS ECU may also be referred to as VSC ECU. On models without VSC, ABS ECU may also be referred to as ABS actuator and ECU.