Kohler CH18

Governor System
4924 690 06 Rev. P KohlerEngines.com
THIRD AND FOURTH DESIGN GCU Troubleshooting Electronic Governor
Failure Condition Possible Causes Equipment Observations Inspection/Testing
Target/Selected
Speed not
Maintained
(Overspeed and/or
Underspeed) (No
hunt or surge)
Loss of GCU power
(B+ or Ground).
(Potentially
Intermittent)
When connection is lost, no DLA
movement will be seen. When
connection is restored, engine speed
will drop to or below idle speed before
returning to target speed position.
Test for GCU power by
turning key to ON position
and inspect for LED lights
to illuminate or test GCU
power (red/B+) wire for
supply voltage and test
ground circuit. Inspect all
connections and wires for
poor connection. Repair
and replace as required.
Target/Selected
Speed Not
Maintained (Over
speed and/or Under
speed) (No hunt or
surge)
Speed Signal
(Potentially
Intermittent)
When connection is lost, no DLA
movement will be seen. When
connection is restored, throttle returns
to target speed position.
View GCU blink key ON
and running codes for
potential trouble code.
Inspect all connections
and wires for poor
connection. Repair and
replace as required.
No Start and/or
ungoverned speed
below 1500 RPM
Throttle fully closed.
No throttle
movement.
While cranking, GCU commands DLA
to open to a predetermined position. If
no movement is seen, engine may not
start due to closed throttle. If engine
starts, engine speed may be below
1500 RPM.
Check system power,
physical binding, and
wiring etc.
No response to
selected speed input
Loss of application
supplied speed
control input signal.
GCU regulates engine speed by
variable input voltage from a customer-
supplied source. When signal is lost,
engine speed will return to idle. When
connection is restored, throttle returns
to target speed position.
Conduct speed input wire
(red w/yellow tracer)
voltage test. (Refer to test
description on page 51 for
more information)
THIRD AND FOURTH DESIGN GCU Blink Codes for Software Stored Codes - Activated when key is turned to
ON position.
Failure Condition Possible Causes Response
Response
Time
LED Diagnostics
Yellow LED Green LED
Speed Error BLINKS ON
Watchdog Interrupt RFI interference Ground to kill,
close carb throttle
plate
BLINKS BLINKS
Overtemp
Software bug
Lightning
Overspeed (Over
4500 RPM for 0.5
seconds sustained)
External noise on ignition input Ground to kill,
close carb throttle
plate
1 second
delay
ON ON
Frozen carb throttle plate
DLA failure
Mechanical bindage
Excessive Battery
Voltage
(> 18v for 0.5
seconds)
Open battery voltage on B+
24 V battery (Not Compatible
with system, 12 V battery only)
Ground to kill,
close carb throttle
plate
0.5
seconds
OFF ON