Capacitive Discharge Ignition Module; Troubleshooting And Testing Cd Ignition Systems; Preliminary Test - Kohler Courage SV470 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
D1
C1
SCS
L2
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.

Preliminary Test

To be certain the reported problem is in the engine
ignition system, it should be isolated from the unit, as
follows.
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