Lock Unit, Tailgate/Trunk Lid
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2009 Volvo S60, 2008 Volvo S60, 2007 Volvo S60, 2006 Volvo S60, and 2005 Volvo S60. However, it is still accessible from the selected car via links, so may be relevant.
Applicable to the S80/S60:
The lock unit in the trunk lid on the S80/S60 actually has no "unlocked" mode. The difference between locked and unlocked mode is whether or not the rear electronic module (REM) activates the lock unit when the switch in the trunk lid is pressed. Opening the trunk lid depends on whether central locking is in unlocked mode or not. There is a lock cylinder in the trunk lid as a mechanical reserve alternative. The lock cylinder is mechanically connected to the lock unit. The trunk lid can be opened via the lock cylinder with the key.
The switch on the trunk lid (S60/S80) and lock unit (3/78) are directly connected to the rear electronic module (REM).