Ignition System; Ignition Control System - Suzuki DF 40 Service Manual

3-11 ENGINE CONTROL SYSTEM

IGNITION SYSTEM

The ignition system used by the DF40/DF50 is a fully transistorized, electronic microcomputer timing ad-
vanced type.
On this system, power is totally supplied from the battery with the ECM controlling all ignition timing func-
tions.
The ignition system is composed of the ignition coil, spark plug and components for system control (ECM,
sensor,switch etc.)
When the ignition switch is "ON", battery voltage (12V) is applied to the circuit as shown in the illustration.
At the calculated time of ignition, the transistor in the ECM turns "OFF", breaking the ground circuit.
In this way, a mutual induction high voltage occurs in the ignition coil secondary side and spark is generated.
Battery
charge
coil
ECM
main
Rectifier &
relay
regulator
30A fuse
Ignition
switch
Battery

IGNITION CONTROL SYSTEM

OUTLINE
Sensors at specific points on the engine monitor current engine conditions and send signals to the ECM.
Based on these signals, the ECM determines the optimum ignition timing and releases voltage to the igni-
tion coils.
Basic sensors
MAP sensor :
Informs ECM of intake manifold pressure.
CKP sensor :
Informs ECM of engine speed and crankshaft angle.
Compensating sensors
Cylinder temperature sensor :
Informs ECM of cylinder temperature.
Switches
CTP switch :
Informs ECM of throttle position (open / closed).
Ignition switch :
Informs ECM of "START" signal.
ECM
CPU
Ignition
coil
Spark
plug
Sensor/switch
signal input
(Voltage)
12V
terminal voltage
ECM
Ignition timing is deter-
mined by a digital map de-
signed in relation to intake
manifold pressure and en-
gine speed.
Ignition timing compensa-
tion.
Signal Signal
Ign.coil Ign.coil
Spark plug
Spark timing
(Time)
Signal
Ign.coil