WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Connectors For Solenoid Valves
Courtesy of VOLVO CARS OF NORTH AMERICA.
Disconnect the connectors for the solenoid valves (S1, S2, SL, STH).
Remove the cable harness from the holders on the control system.