Seat belt buckle

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.

Fig 1: Locating Seat Belt Buckles

Courtesy of VOLVO CARS OF NORTH AMERICA.

The two front seat belt buckles have Hall sensors which detect whether or not the seat belts are engaged. They are connected differently depending on the model year:

Model year 1999-2002: The two front seat belt buckles are directly connected to the central electronic module (CEM). The central electronic module (CEM) then sends the data onwards on the controller area network (CAN) to the supplemental restraint system (SRS) module
Model year 2003-: The two front seat belt buckles are directly connected to the supplemental restraint system module (SRS).

This data is used to set the activation level of the airbags and to determine whether or not the seat belt tensioners need to be activated. If a fault is detected in the seat belt buckles or in the terminal for the seat belt buckles, the activation level of both the driver and passenger airbags is set as if the occupant is not wearing a seat belt. The seat belt tensioner will still function as if the occupant is wearing a seat belt however.

NOTE:

Applies to model year 1999-2002. In the event of a fault, either in the Hall sensor or wiring for the front seat belt buckles, a diagnostic trouble code (DTC) is stored locally in the central electronic module (CEM). This diagnostic trouble code (DTC) is also stored in the supplemental restraint system (SRS) module. The diagnostic trouble code (DTC) in the supplemental restraint system (SRS) module cannot be erased before the fault has been completely remedied and the corresponding code erased from the central electronic module (CEM).