Ignition Control Module
WARNING: This page is about a different car, the 2005 Saturn L300. However, it is still accessible from the selected car via links, so may be relevant.
Each ICM has the following circuits:
- An ignition voltage circuit
- A ground
- Three control circuits, one for each ignition coil
The ECM can command each ignition coil ON by grounding the control circuit of the ignition coil. The control circuit is pulse width modulated ON/OFF in order to precisely control the spark event.
The spark plugs are connected to each coil by a short boot. The boot contains a spring that conducts the spark energy from the coil to the spark plug. The spark plugs are tipped with platinum for long wear and higher efficiency.