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 Terminal Removal Tool Inserted In Cavity On Connector Side Of Housing
Courtesy of VOLVO CARS OF NORTH AMERICA.
A terminal removal tool is usually required to release the locking tab/locking catch so that the cable terminal can be extracted and removed.