Transmission Position Sensor/Switch: Description and Operation

TRANSAXLE RANGE (TR) SELECTOR SWITCH





The Transaxle Range (TR) Selector is attached to the valve body and contains six fluid pressure switches and the transaxle temperature sensor (refer to the separate description of the temperature sensor). Five of the fluid pressure switches (PRND4, DRIVE, LO, D21, REV) are normally open and are used to indicate the position of the manual valve. The PCM uses this information to control line pressure, TCC apply and release and shift solenoid operation.
The RELEASE pressure switch is a normally closed pressure switch. This switch is used as a diagnostic tool to confirm that the TCC is actually OFF when it has been commanded OFF by the PCM.





Diagram





Chart

Each fluid pressure switch produces either an open or ground to the PCM depending on the presence of fluid pressure at the switches. The sequence of open and closed switches produces a combination of voltage readings that are monitored by the PCM (see chart and switch logic diagram).
The PCM measures TR switch. signal voltage from each pin to ground and compares the voltage to a TR switch combination chart stored in the PCM memory. If the PCM does not recognize the switch sequence, a diagnostic code will be set as a result. A diagnostic code may also be set if the TR switch sequence indicates a gear range selection that conflicts with other sensory inputs to the PCM.

Important: Resistance should be measured with the engine running. When the transaxle pass thru connector is disconnected from the vehicle harness and the engine is running, multiple diagnostic codes will be set. Be sure to clear these codes when finished with this procedure.