Capacitive Discharge Ignition Module; Troubleshooting And Testing Cd Ignition Systems; Preliminary Test - Kohler Courage SV470-600 Service Manual

Section 7
Electrical System and Components
L1
Figure 7-3. Capacitive Discharge Ignition Module.
Operation
As the flywheel rotates, and the magnet passes the
ignition module, the magnetic field induces current in
the input coil (L1). The current pulse is rectified by a
diode (D1) and charges a high-voltage capacitor (C1).
As the magnet completes its pass, it induces current in
a small triggering coil (L2), which turns on the
semiconductor switch (SCS). With the switch on, the
charged capacitor is directly connected to the primary
winding (P) of the transformer (T1). As the capacitor
discharges through the primary, the current initiates a
fast-rising flux field in the transformer core. The flux
field induces a high voltage in the secondary winding
(S) of the transformer. The high voltage pulse is
delivered to the spark plug, where it arcs across the
electrode gap and ignites the fuel-air mixture in the
combustion chamber.
Troubleshooting and Testing CD Ignition
Systems
The CD ignition system is designed to be trouble free
for the life of the engine. Other than periodically
checking/replacing the spark plug, no maintenance or
timing adjustment is necessary or possible. The
ignition module automatically controls the timing of the
spark. Mechanical systems do occasionally fail or
break down, however, so the following troubleshooting
information is provided to help systematically
determine the cause of a reported problem.
Reported ignition problems are most often due to poor
or loose connections. Before beginning the test
procedure check all external wiring, including ground
leads for wiring harness and rectifier-regulator (if so
equipped). Be certain all ignition-related wires are
connected, including the spark plug lead, and all
terminal connections fit snugly. Make sure the ignition
switch is in the run position.
7.4
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D1 C1
SCS
L2

Preliminary Test

To be certain the reported problem is in the engine
ignition system, it should be isolated from the unit, as
follows.
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T1
P
S
NOTE: The CD ignition systems are sensitive to
excessive load on the kill lead. Customer
complaints of hard starting, low power, or
misfire under load may be due to excessive
draw on the kill circuit. Disconnect any
auxiliary kill wires or safety switches
connected to the kill circuit and operate the
engine to determine if the reported problem is
gone.
1. Locate the plug connectors where the wiring
harnesses from the engine and unit are joined.
Separate the connectors and separate the white
"kill" lead from the engine connector. Rejoin the
connectors and position or insulate the kill lead
terminal, so it cannot touch ground. Try to start
the engine to verify whether the reported problem
is still present.
a. If the problem is gone, the electrical system
on the unit is suspect. Check the key switch,
wires, connections, safety interlocks, etc.
b. If the problem persists, continue with the
following troubleshooting procedure. Leave
the kill lead isolated until all testing is
completed.
Spark
Plug