Circuit Description

A Direct Ignition System (DIS) is used on this vehicle. The DIS improves the ignition timing accuracy, reduces high-voltage loss, and does not require a distributor, which enhances the overall reliability of the ignition system.

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 the ignition timing and outputs the ignition signals (IGTs) for each cylinder. Using the IGT, the ECM turns on and off the power transistor inside the igniter, which switches on and off current to the primary coil. When current to the primary coil is cut off, high-voltage is generated in the secondary coil and this voltage is applied to the spark plugs to create sparks inside the cylinders. As the ECM cuts current to the primary coil, the igniter sends back the ignition confirmation signal (IGF) for each cylinder ignition to the ECM.

Fig 1: Ignition Coil With Igniter Circuit Description

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Fig 2: DTC P0351, P0352, P0353, P0354, P0355, P0356, P0357 & P0358 Detection Condition & Trouble Area Table

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Reference: The waveform of IGT and IGF signal 

During the engine idling, check the waveform between terminals IGT1 to IGT8 and E1, and IF1L, IF2L, IF1R or IF2R and E1 of the E2, E3 and E4 ECM connectors.

HINT:

The wavelength becomes shorter as engine RPM increases.

1. Igniter IGT signal (from ECM to igniter)
2. Igniter IGF signal (from igniter to ECM)
   Fig 3: IGT & IGF Signal Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002