Ignition coils
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.
The ignition coils ignite the fuel / air mixture on command from the engine control module (ECM). The signal is re-transmitted so that the control module knows that it worked.
Each ignition coil has its own integrated power stage.
The ignition coils are in the sparkplug wells above each spark plug.
The ignition windings can be diagnosed by the Engine control module (ECM) and can be activated using VIDA.