Transmission Input Speed Sensor

WARNING: This page is about a different car, the 2003 Dodge Grand Caravan, 2003 Dodge Caravan, 2003 Chrysler Voyager, and 2003 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.

The input speed sensor is a two-wire magnetic pick-up device that generates an AC voltage signal as rotation occurs. See Fig 1 . It is threaded into the transaxle case and sealed with an "O" ring. See Fig 2 . The sensor is considered a primary input to the Powertrain/Transmission Control Module (PCM/TCM). The input speed sensor provides information on how fast the input shaft is rotating. As the teeth of the input clutch hub pass by the sensor coil, an AC voltage signal is generated and sent to the PCM/TCM. See Fig 3 . The PCM/TCM interprets this information as input shaft RPM. The PCM/TCM compares the input speed signal with the output speed signal to determine transmission gear ratio, speed ratio error detection and clutch volume index. The PCM/TCM also compares the input speed signal and the engine speed signal to determine torque converter clutch slippage and torque converter element speed ration.

Fig 1: Locating Input Speed Sensor

Courtesy of CHRYSLER CORP.

Fig 2: View of Input Speed Sensor & "O" Ring

Courtesy of CHRYSLER CORP.

Fig 3: Identifying Sensor Relation To Input Clutch Hub

Courtesy of CHRYSLER CORP.