Theory Of Operation

The purpose of this diagnostic is to check the electrical performance of the input speed sensor circuit. The sensor is located in front of the target wheel which is connected to the transmission input shaft, and measures the rotation of the target wheel. The input speed sensor is a Hall Effect sensor with a pulse train output frequency range of 50 ~ 8000 RPM. The normal operating output voltage range of the input speed sensor is in the range of 0.8 to 1.5 V. The malfunction conditions detected by this diagnostic include short to battery, short to ground, and open circuit failures. These malfunctions are determined based upon the A/D conversion value.