WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Pin Housing Opening
Courtesy of VOLVO CARS OF NORTH AMERICA.
First remove the pin housing from the outer shell.
Open the pin housing secondary locking by turning the two rings as shown. A "click" indicates that the secondary locking has disengaged.