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 Transmission Control Module (TCM)
Courtesy of VOLVO CARS OF NORTH AMERICA.
The transmission control module (TCM) is located by the engine control module (ECM) inside the center console under the dashboard.