900 Turbo Convertible L4-1985cc 2.0L DOHC Turbo EFI (1994)
Ignition Discharge Module: Description and Operation
Ignition
The ignition discharge module is mounted on the valve cover over the spark plugs. There are four ignition coils in the ignition discharge module,
the secondary windings of which are directly connected to the spark plugs.
The ignition discharge module is supplied with Batt+ from the main relay and grounded at grounding point G7P.
When the main relay operates, Batt+ is supplied to the ignition discharge module, which converts 12 V to 400 V DC voltage which is stored in a
capacitor. The 400 V voltage is connected to one pole of the primary windings of the ignition coils.
Four trigger wires are connected to the ignition discharge module from Trionic ECM pin 9 (cyl. 1), pin 10 (cyl. 2), pin 11 (cyl. 3) and pin 12 (cyl.
4).
When the ECM grounds pin 9, the other pole of the primary winding for cyl. 1 will be grounded and 400 V transformed up to max. 40 kV in the
ignition coil for cyl. 1. Ignition takes place in the same way for cyl. 2, 3 and 4.
If there is an open circuit in the power supply or ground to the ignition discharge module, the engine will not start.
If there is an open circuit on any of the trigger leads, the cylinder concerned will not fire.
