Output Speed Sensor
SPEED SENSOR OUTPUTDESCRIPTION
The Output Speed Sensor is a two-wire magnetic pickup device that generates an AC voltage signal as rotation occurs. It is threaded into the transaxle case (Fig. 359), sealed with an O-ring (Fig. 360), and is considered a primary input to the Transmission Control Module (TCM).
OPERATION
The Output Speed Sensor provides information on how fast the output shaft is rotating. As the rear planetary carrier park pawl lugs pass by the sensor coil (Fig. 361), an AC voltage is generated and sent to the TCM. The TCM interprets this information as output shaft rpm.
The TCM compares the input and output speed signals to determine the following:
- Transmission gear ratio
- Speed ratio error detection
- CVI calculation
VEHICLE SPEED SIGNAL
The vehicle speed signal is calculated from the Output Speed Sensor. The TCM converts this OSS signal into a roughly 8000 pulse per mile vehicles speed signal (using pinion factor information programmed into its memory), and sends it to the PCM. The PCM, in turn, sends the vehicle speed message across the PCI Bus to the Instrument Cluster to display vehicle speed to the driver.