Transmission Position Sensor/Switch: Description and Operation

DESCRIPTION
The Transaxle Range (TR) switch (formerly called a PRNDL, P/N or NSBU switch) is mounted externally on the transaxle at the manual shaft. The TR switch provides information to the PCM about the selected gear range of the transaxle. The TR switch identifies whether the transaxle is in PARK/NEUTRAL (P/N) or any of the five drive ranges (R/D4/D3/D2/D1). The TR switch is also used to illuminate the backup lamps when the transaxle is in REVERSE (R).

PCM INPUT
The PCM uses TR switch status for idle speed control, and also as a backup to the transaxle pressure switch. If the transaxle pressure switch is faulty, the PCM will select a transaxle gear based on TR switch status. A faulty TR switch should set a Diagnostic Trouble Code.