DeVille V8-4.9L VIN B (1995)
Transmission Position Switch/Sensor: Description and Operation
Transaxle Range Switch
DESCRIPTION
The Transmission 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 Powertrain Control Module (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).
The PCM uses TR switch status for idle speed control. A faulty TR switch should set a Diagnostic Trouble Code.
