DTC P1561 (18): Motor Commutation Sensor B Circuit Low Input: General Description

The motor control module (MCM) monitors the motor rotor position to control motor output. The motor commutation sensor outputs six pulsing signals for each motor revolution.

The Low/High combination of the motor commutation sensor signals and its transition state follow a specific pattern (shown above), and normally they agree.

The MCM monitors the motor commutation sensor B (CMB) phase when the High/Low combination of the motor commutation sensor A (CMA) and the motor commutation sensor C (CMC) input pulses change.

When the CMA signal is changing to Low or the CMC signal is changing to High during normal operation, the transition state of the CMB is High. If the CMB signal is low a certain number of times within a specified duration, a malfunction of the CMB signal is detected and a DTC is stored.