Kohler Command Pro EFI ECH940 Service Manual page 59

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. If Kohler diagnostic software is available, review "Safety System Active" status in Data Display screen. If yes is
displayed, equipment safety circuit is active (seat switch/PTO switch/Safety interlocks, etc.). This must be
corrected prior to continuing testing.
If diagnostic software is not available, 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.
Test for Spark
NOTE: If 2 testers are available, testing can be performed simultaneously for both cylinders. However, if only 1 tester
is available, 2 individual tests must be performed. Side not being tested must have spark plug lead connected
or grounded. Do not crank engine or perform tests with 1 spark plug lead disconnected and not grounded, or
permanent coil damage may occur.
1. With engine stopped, disconnect 1 spark plug lead. Connect spark plug lead to post terminal of spark tester and
attach tester clip to a good engine ground.
2. Crank engine over, establishing a minimum of 550-600 RPM, and observe tester(s) for spark.
3. Repeat spark test on opposite cylinder if cylinders are being tested individually.
Condition
One side is not fi ring.
Tester shows spark but engine
misses or won't run on that cylinder.
Neither side is fi ring.
Both cylinders have good spark but
engine runs poorly or existing plug
condition is questionable.
1 cylinder has good spark and other
cylinder has no or intermittent spark.
62 690 13 Rev. A
Possible Cause
Electrical System
Ignition or Electrical System
Possible Cause
Wiring and Connections
Spark Plug(s)
Ignition Switch/EFI System/Kill Lead Recheck position of ignition switch
Spark Plug(s)
Ignition
KohlerEngines.com
Electrical System
Conclusion
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 aff ected, test ignition coils.
Conclusion
Check all wiring, connections, and
terminals on that side. If wiring is
okay, replace ignition coil and retest
for spark.
Try new spark plug(s).
and check for shorted kill lead.
Install new spark plug(s) and retest
engine performance.
Test ignition coils and connections.
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