DTC 14

DTC 14 Ignition Signal Circuit






CIRCUIT DESCRIPTION
The Engine Control Module (ECM) determines the ignition timing, turns ON Tr1 at a predetermined angle (°CA) before the desired ignition timing and outputs an ignition signal (IGT) "1" to the distributor, or Integrated Ignition Assembly (IIA).

Since the width of the IGT signal is constant, the dwell angle control circuit in the distributor, 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 distributor 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.


WIRING DIAGRAM FOR IGNITION SIGNAL CIRCUIT





CIRCUIT INSPECTION PROCEDURE