Ignition System: 1H-1
Engine
Ignition System
General Description
Ignition System Construction
S7RS0B1801001
The ignition system is an electronic (distributorless) ignition system. It consists of the parts as described below.
• ECM
It detects the engine and vehicle conditions through the signals from the sensors, determines the most suitable
ignition timing and time for electricity to flow to the primary coil and sends a signal to the ignitor (power unit) in the
ignition coil assembly.
• Ignition coil assembly (including an ignitor)
The ignition coil assembly has a built-in ignitor which turns ON and OFF the current flow to the primary coil
according to the signal from ECM. When the current flow to the primary coil is turned OFF, a high voltage is induced
in the secondary coil.
• High-tension cords and spark plugs
• CMP sensor (Camshaft position sensor) and CKP sensor (Crankshaft position sensor)
Using signals from these sensors, ECM identifies the specific cylinder whose piston is in the compression stroke,
detects the crank angle and adjusts initial ignition timing automatically.
• TP sensor, ECT sensor, MAP sensor, MAF sensor, IAT sensor, knock sensor and other sensors / switches
Although this ignition system does not have a distributor, it has two ignition coil assemblies (one is for No.1 and No.4
spark plugs and the other is for No.2 and No.3 spark plugs). When an ignition signal is sent from ECM to the ignitor in
the ignition coil assembly for No.1 and No.4 spark plugs, a high voltage is induced in the secondary coil and that
passes through the high-tension cords and causes No.1 and No.4 spark plugs to spark simultaneously. Likewise,
when an ignition signal is sent to the ignitor in the other ignition coil assembly, No.2 and No.3 spark plugs spark
simultaneously.
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