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Ignition discharge module
346
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No.1 -·
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Ignition
+30
230
The ignition discharge module is mounted on the
camshaft cover over the spark plugs. There are 4
ignition coils in the ignition discharge module, the
secondary windings of which are connected directly
to the spark plugs.
The ignition discharge module is supplied with power
(B+) from the main relay and connected to ground at
grounding point G7P.
When the main relay operates, power (B+) is sup-
plied to the ignition discharge module which converts
12 V to 400 V d.c. and charges a capacitor with it.
This voltage (400 V) is connected to one pole of the
primary windings of the 4 ignition coils.
Four trigger leads are connected to the ignition dis-
charge module from Trionic ECM pin 9 (cyl. 1 ), pin 1 0
(cyl. 2), pin 11 (cyl. 3) and pin 12 (cyl. 4).
When the engine control module grounds pin 9, the
other pole of the primary winding of the ignition coil
for cylinder 1 will be grounded (via the B+ input of the
ignition discharge module) and the 400 V trans-
formed to a maximum of 40,000 V. Ignition for cylin-
ders 2, 3 and 4 takes place in the same way.
If there is an open circuit in the power supply or a
ground connection to the ignition discharge module,
the engine will not start. -
589
229
Saab 9000
346
Technical Description 35
G7P
589
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