Checking and reinstalling the balls in the valve housing
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.
2 large balls (373).
4 smaller balls (372).
Inspect one ball at a time. Ensure that there is no dirt on the ball and that the surface are smooth and shiny.
Check the four balls in the control system housing. Follow the same procedure as above.