Ignition Control Module: Description and Operation

Power Stage Location:

The power output stage is the device which controls primary current supply to the ignition coil. It is mounted to the coil and consists of a power transistor and integrated circuit.

Power Stage Diagram:

The power output stage receives a triggering signal from the CIS-E Motronic control unit. The voltage signal (trigger) to the power output stage turns it "ON". In this "ON" state, current flows through the primary circuit of the ignition coil. When the Motronic control unit determines that it is time for coil discharge, the current to the power output stage is momentarily interrupted and the transistor turns "OFF". This interrupts primary current flow to the coil creating a high voltage discharge in the secondary circuit of the coil. In this manner, the power output stage operates like a solid state pair of ignition points.