Ignition System (Digital Ignitor); Description - Suzuki GSF1200S 2001 Service Manual

IGNITION SYSTEM (DIGITAL IGNITOR)

DESCRIPTION

The fully transistorized ignition system consists of the following components: a signal generator (which is
made up of the signal generator rotor and pickup coil), ignitor (including a 8-bit microcomputer and a 10 MHz
ceramic vibrator), throttle position sensor, two ignition coils and four spark plugs. The ignition timing is pro-
grammed and stored in the ignitor's ROM (Read Only Memory).
The signal generator is mounted on the right end of the crankshaft. The induced signal in the signal gen-
erator is sent to the wave-form arrangement circuit and the CPU receives this signal and calculates the best
ignition timing from the signal of the ceramic vibrator, throttle position sensed by throttle position sensor and
data stored in the ROM. The CPU outputs the signal to the transistor of the ignition coil output circuit which is
connected to the primary windings of the ignition coils which is turned "off" and "on" accordingly. Thus, it
induces the secondary current in the ignition coil's secondary windings and produces the spark between the
spark plug gaps.
The ignition cutoff circuit is incorporated in the ignitor to prevent the engine from overreving. If the engine
speed reaches 10 900 r/min, this circuit will cutoff the ignition primary current for the #1 and #4 spark plugs.
"
The engine is capable of running at over 10 900 r/min without a load, even if the ignition cutoff
circuit is in effect; however, this may cause engine damage. Therefore, never run the engine over
10 900 r/min without a load.
Waveform
Y/W
arrange-
ment
circuit
Signal generator
WIRE COLOR
W : White
O : Orange
R : Red
Y : Yellow
Bl : Blue
Ignitor
Ignitor power
source circuit
[ ]
Central
Processing
Unit
Bl Y
Throttle position sensor
O/W : Orange with White tracer
B/Y : Black with Yellow tracer
Y/W : Yellow with white tracer
O/Y : Orange with Yellow tracer
O/B : Orange with Black tracer
O/W
Ceramic vib
I.G. coil output
circuit
To tachometer
B/R : Black with Red tracer
B/W : Black with White tracer
B/Bl : Black with Blue tracer
B/G : Black with Green tracer
ELECTRICAL SYSTEM
Engine
Turn signal/
stop switch
side-stand relay
Fuse
(10A)
Ignition
coils
Spark plugs
6-27
Ignition
switch
Main
fuse
(30 A)
Battery
(12V
8AH)