Vehicle Speed Sensor: Avalon

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 vehicle speed signal to Engine Control Module (ECM). On models with traction control, ABS ECU may also be referred to as ABS & BA (Brake Assist) & TRAC & Vehicle Skid Control (VSC) ECU. On models without traction control, ABS ECU may also be referred to as ABS actuator and ECU. On all applications, if problem exists with vehicle speed signal, a Diagnostic Trouble Code (DTC) may be stored in Engine Control Module (ECM). See TESTING PROCEDURE under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article for retrieving of DTCs.