Kohler command pro CH742 Service Manual page 34

Electrical System
Ignition Systems
These systems use a capacitive discharge (CD) coil. With CDI fi xed timing, ignition timing and spark remains constant
regardless of engine speed. Timing of spark is controlled by location of fl ywheel magnet group as referenced to
engine TDC. MDI adjustable timing uses a digital microprocessor which is located in ignition modules. Ignition timing
varies depending upon engine speed with this system.
A typical ignition system consists of:
● 1 magnet assembly which is permanently affi xed to fl ywheel.
● 2 electronic capacitive-discharge ignition modules which mount on engine crankcase.
● 1 kill switch (or key switch) which grounds modules to stop engine.
● 2 spark plugs.
A Spark Plug(s)
Flywheel Stator
E
Assembly
I Rectifi er-Regulator
M Starter Solenoid Tang
Alternate Ignition Kill
Q
(–)
U Ignition Kill
Y Black (Ground)
AC Oil Sentry Light
™
AG Accessory
AK Key Switch Ground
AO Battery Negative
Electronic Ignition Systems Tests
NOTE: Ignition tester must be used to test ignition on these engines. Use of any other tester can result in inaccurate
fi ndings. Battery on unit must be fully charged and properly connected before performing tests (a battery that
is hooked up or charged backward will crank engine but it won't have spark). Be certain drive is in neutral and
all external loads are disconnected.
Test Ignition Systems
NOTE: If engine starts or runs during testing, you may need to ground kill lead to shut it down. Because you have
interrupted kill circuit, it may not stop using switch.
Isolate and verify trouble is within engine.
1. Locate connectors where wiring harnesses from engine and equipment are joined. Separate connectors and
remove white kill lead from engine connector. Rejoin connectors and position or insulate kill lead terminal so it
cannot touch ground. Try to start engine to verify whether reported problem is still present.
Condition
Problem goes away.
Problem persists.
34
B Oil Pressure Switch
F Ignition Module
J Oil Sentry Kill (Green)
™
N Starter Solenoid Stud
R White
V Red
Z Intake Manifold Screw AA
AD Connector
AH Battery
AL Rectifi er
Possible Cause
Electrical System
Ignition or Electrical System
KohlerEngines.com
C Oil Sentry (Green)
™
Non-Smart Spark
G
™
Ignition
K Violet B+
O Fuse
S Accessory Terminal (+)
W Carburetor
Black
AE Magneto
AI Starter
AM Blue/Red
Check key switch, wires, connections,
safety interlocks, etc.
Leave kill lead isolated until all testing
is completed.
Identify white kill lead of engine
wiring harness connector. Establish
a connection to a known good
ground location. Engine should kill
completely. If not or only one cylinder
is affected, check ignition modules
and white kill lead connection for
affected module.
D White Kill
Rectifi er-Regulator
H
Connector
Solenoid Shift Starter
L
Assembly
P Blue
T Yellow
X Carburetor Solenoid
Oil Sentry Panel
AB
™
Light/Remote Light
AF Key Switch
AJ Ground
AN Battery Positive
Conclusion
24 690 34 Rev. D