Circuit Description

WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

A Direct Ignition System (DIS) 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 1-cylinder ignition system which ignites one cylinder with one ignition coil. In the 1-cylinder ignition system, the one spark plug is connected to the end of the secondary winding. High voltage generated in the secondary winding is applied directly to the spark plug. The spark of the spark plug passes 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 supplied to the spark plug that are connected to the end 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. DTCs are caused by IGF signal not input to ECM for 2 or more ignitions. Condition is repeated 3 times consecutively during 6 consecutive IGT signals while engine is running. Possible causes are:

Ignition system.
Open or short in IGF or IGT1-IGT6 circuit from ignition coil with igniter to ECM.
No. 1-No. 6 ignition coil with igniter.
ECM.