Electronic Spark Timing

The Electronic Spark Timing (EST) system consists of an ignition module, ignition secondary, Electronic Control Module (ECM), and pick up coil. The distributor has four wires that connect the ignition module to the ECM. These circuits perform the following functions:

1. The ignition module is a switching device which can operate the primary circuit of the ignition coil, provide a square wave reference signal to the ECM, and switch circuits for the ECM to control the operation of the ignition coil primary circuit.

2. The ignition secondary consists of the ignition coil, rotor, distributor cap, plug wires, and spark plugs. These components supply the high voltage to fire the spark plugs.

3. The ECM is a microprocessor device that receives input from the ignition module, Manifold Absolute Pressure (MAP) sensor, and Coolant Temperature Sensor (CTS) and calculates an output signal to operate the ignition primary circuit.

4. The pick up coil is a device that generates an alternating current signal to determine crankshaft position.