DTC 14

CODE - 14 IGNITION SIGNAL CIRCUIT

Circuit Description

The ECM determines the ignition timing, turns on Tr1 at a predetermined angle (degree CA) before the desired ignition timing and outputs an ignition signal (IGT) "1" to the IIA (Distributor).

Since the width of the IGT signal is constant, the dwell angle control circuit in the IIA determines the time the control circuit starts primary current flow to the ignition coil based on the engine speed and ignition timing one revolution ago, that is, the time the Tr2 turns on.

When it reaches the ignition timing, the ECM turns Tr1 off and outputs the IGT signal "0". This turns Tr2 off, interrupting the primary current flow and generating a high voltage in the secondary coil which causes the spark plug to spark. Also, by the counter electromotive force generated when the primary current is interrupted, the IIA sends an ignition confirmation signal (IGF) to the ECM. The ECM stops fuel injection as a fail safe function when the IGF signal is not input to the ECM.




Detecting Condition




Inspection Using Oscilloscope

- During cranking or idling, check waveform between terminal IGT, IGF and E1 of engine control module.

NOTE: The correct waveform appears as shown in the illustration, with rectangle waves.




Diagnostic Chart




Wiring Diagram

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Inspection Procedure