Ignition Power Stage: Description and Operation

PURPOSE
The power stage functions as an electronic switch controlling the current in the ignition coils on command from the ECU. This function is comparable to the operation of the points in a mechanical ignition system, in that it opens and closes the coil primary ground connection.

OPERATION
Depending on monitored engine speed and supply voltage, dwell angle is determined and ignition output is adapted to that required at any given moment. The distributor only functions as a rotary switch directing coil secondary output to the spark plugs.

Ignition timing is ECM calculated according to air mass meter and crankshaft sensor inputs. With this information, the ECM initiates one of 256 programmed timing angle selections based on 16 engine load levels and 16 different engine speeds.

Ignition Amplifier:

LOCATION
Right front of engine compartment.