General Information

Component Location





General Description

The Steering wheel angle sensor uses two sensors (A-sensor and B-sensor) to determine the direction of the rotation.
The main components of each sensor are LED, photo transistor and slit plate.
The slit plate, which has 45 holes, is installed between LED and photo transistor, and generates signals if slit plate rotates according to the steering wheel rotation.
The sensor signals are generated by photo transistor which is driven whenever the light passes through the holes. The HECU detects operating speed and direction of the steering wheel by this input signal, and the signal is used to input signal for anti-roll control.

DTC Description

This monitoring function monitors the changing point of N-signal with measured steering angle from ST1 and ST2.
If N-signal changing point differs more than predefined degree, the failure is detected.
If there is no variation of the steering wheel angle for predefined time ECU detect the failure.

DTC Detecting Condition





Diagnostic Circuit





Signal Waveform












Fig 1) Normal waveform of steering angle sensor with turning left after ENG "ON" : Output signal change ("LOW" -> "HIGH") is detected first in ST1.
Fig 2) Normal waveform of steering angle sensor with turning right after ENG "ON" : Output signal change ("LOW" -> "HIGH") is detected first in ST2.
Fig 3) Normal waveform of steering angle sensor being center position after ENG "ON" : Output signal change ("HIGH (approx 3.5V)" -> "LOW") is detected when steering wheel is passing by on center position.
** "LOW" : approx 1.5V, "HIGH" : approx 3.5V.