Tacoma Extra Cab 4WD L4-2693cc 2.7L DOHC MFI (1997)
Igniter: Description and Operation
CIRCUIT DESCRIPTION
A DIS (Direct Ignition System) has been adopted. The DIS improves the ignition timing accuracy, reduces high-voltage loss and enhances the
overall reliability of the ignition system by eliminating the distributor. The DIS is a 2-cylinder simultaneous ignition system which ignites 2
cylinders simultaneously with one ignition coil. In the 2-cylinder simultaneous ignition system, each of the 2 spark plugs is connected to the end of
the secondary winding. High voltage generated in the secondary winding is applied directly to the 2 spark plugs. The sparks of the 2 spark plugs
pass simultaneously from the center electrode to the ground electrode.
The ECM determines ignition timing and outputs the ignition signals (IGT) for each cylinder. Based on IGT signals, the power transistors in the
igniter cuts off the current to the primary coil in the ignition coil is supplied simultaneously to the two spark plugs via the high-tension cords that
are connected to the both ends of the secondary coil. At the same time, the igniter also sends an ignition confirmation signal (IGF) as a fail-safe
measure to the ECM.
