Line pressure solenoid SLU, SLS, SLT
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2007 Volvo V70, 2006 Volvo V70, 2005 Volvo V70, 2004 Volvo V70, and 2003 Volvo V70. However, it is still accessible from the selected car via links, so may be relevant.
Activating line pressure solenoid STH.
"Clicking sound" in the transmission (use a stethoscope) and the current should vary.