Transmission speed sensor, input speed
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.
The value indicates the input speed from the transmission speed sensor. The speed can be generated with the engine idling and the gear selector in P/N position. If the gear selector is in any other position, a gear is engaged and the transmission input shaft is connected to the output shaft and an RPM will not be indicated until the car is driven. Depending on slippage in the torque converter the transmission speed and the engine speed will differ when the lock-up function is not engaged. With lock-up engaged the transmission speed should be the same as engine speed (RPM).