DTC P0351: Ignition Coil "A" Primary / Secondary Circuit; DTC P0352: Ignition Coil "B" Primary / Secondary Circuit; DTC P0353: Ignition Coil "C" Primary / Secondary Circuit; DTC P0354: Ignition Coil "D" Primary / Secondary Circuit: Description

HINT: 

• These DTCs indicate malfunctions relating to the primary circuit.
• If DTC P0351 is set, check the No. 1 ignition coil assembly circuit.
• If DTC P0352 is set, check the No. 2 ignition coil assembly circuit.
• If DTC P0353 is set, check the No. 3 ignition coil assembly circuit.
• If DTC P0354 is set, check the No. 4 ignition coil assembly circuit.

A Direct Ignition System (DIS) is used on this vehicle.

The DIS is an ignition system in which each cylinder is ignited by it's own ignition coil assembly and spark plug. The secondary wiring of each ignition coil generates a powerful voltage which is applied directly to each spark plug. The spark passes from the center electrode of the spark plug to the ground electrode.

The ECM determines the ignition timing and transmits the ignition (IGT) signals to each cylinder. Using the IGT signal, the ECM turns the power transistor inside the igniter on and off. The power transistor, in turn, switches on and off the current to the primary coil. When the current to the primary coil is cut off, a powerful voltage is generated in the secondary coil. This voltage is applied to the spark plugs, causing them to spark inside the cylinders. As the ECM cuts the current to the primary coil, the igniter sends back an ignition confirmation (IGF) signal to the ECM, for each cylinder ignition.

Fig 1: Identifying Direct Ignition System Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Reference: Inspection using an oscilloscope.

Fig 2: Identifying Waveform 1

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT: 

While idling the engine, check the waveform between terminals IGT (1 to 4) and E1, and IGF and E1 of the ECM connector.