Theory Of Operation

The purpose of this diagnostic is to check the electrical performance of the transmission fluid temperature (TFT) sensor circuit. The TFT sensor is an analog device for which the TCM performs A/D conversion every 80 msec. The malfunction conditions detected by this diagnostic include shorted to battery, short to ground, and open circuit failures. If the TFT sensor circuit is out of range high (shorted to battery or open circuit) or out of range low (shorted to ground), a fault is detected.