Theory Of Operation

The purpose of the diagnostic is to check the turbine speed sensor circuit for electrical failures by continuously monitoring the sensor output circuit for voltage high, low, or open conditions. The turbine speed sensor is a Hall Effect sensor that has an output range that alternates between normal high and normal low voltages as the turbine tone wheel rotates. If the measured turbine speed sensor output circuit voltage is greater than or equal to a calibrated high threshold (circuit high) or is less than or equal to a calibrated low threshold (circuit low or open) for a calibrated amount of time, a DTC will set.