Ignition Control Module: Description and Operation

Distributor:

The Igniter, part of the pick-up coil in the distributor, is a switching device that activates the primary ignition coil circuit. The ECU transmits a primary current "OFF" signal to the igniter to trigger the coil. When the atmospheric pressure sensor detects high altitude (above 1000 meters, 3280 feet), the ECU advances timing approximately 6° to compensate for engine power loss. The timing is also automatically advanced approximately 6° at idle when the A/C is "ON."

The ECU calculates input from these devices to regulate ignition timing:

Throttle sensor
Atmospheric pressure sensor
Idle switch
Neutral and clutch switch (M/T)
Inhibitor switch (A/T)
A/C switch
Ignition switch ("START" position)
Test connector (for base timing adjustment)