Operation Principle of the Transistorized Type with ESA


1. The engine ECU receives the signals from various sensors, calculates the optimal ignition timing, and sends an ignition signal to the igniter. (The engine ECU controls the timing advance.)

2. The igniter receives the ignition signal and causes the primary current to flow intermittently.

3. The ignition coil, to which the primary current has been shut off abruptly, generates a high-voltage current.

4. The distributor distributes the highvoltage current generated by the secondary coil to the spark plugs.

5. The spark plugs receive the highvoltage current and ignite the air-fuel mixture.

How to check if Ignition System works?

1. Check initial timing

(1) Allow the engine to warm up and short the terminals TE1 and E1 on DLC1, or TC and CG on DLC3.

(2) Connect the pick-up of the timing light to the power source line of the ignition coil.

(3) Inspect the ignition timing with throttle valve fully closed.


The initial timing is set by shortening TE1 and E1 on DLC1, or TC and CG on DLC3. There are two types of pick-up for the timing light:

Detection of the primary current ON/OFF or detection of the secondary voltage. Since the ignition timing is advanced when the throttle valve is opened, the throttle valve should be inspected while fully closed. Incorrect initial timing may cause decreases in output, worsened fuel consumption or knocking.

2. Check spark plug

A spark will not be generated when there are cracks, a dirty electrode, wear or too large of a gap. When the plug gap is too small, quenching is possible. In this case, the fuel does not ignite even if a spark is generated.


If a spark plug of an improper heat range is used, it may cause the spark plug to accumulate carbon on the electrode or to melt.

3. Spark test

(1) Disconnect all injector connecters so that fuel cannot be injected.

(2) Remove the ignition coil (with igniter) and spark plug.

(3) Re-install the spark plug in the ignition coil.

(4) Connect the connectors with it, and ground the spark plug. Check that the spark plug generates a spark when cranking at this condition. This test determines which cylinder does not have a spark.


Do not crank for the spark test over 5 – 1seconds.

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