Governor System
4524 690 06 Rev. P KohlerEngines.com
FIRST 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 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.
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.
Engine may not start due to closed
throttle. If engine starts, engine speed
will 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)
FIRST DESIGN GCU Basic Electrical Diagram of Electronic Governor System
B+
10
8
12
13
14
1
2
6
7
1B
1A
2A
2B
Power
Device
Ground
Speed Signal
DLA Driver
Controls
Kill Tab (Speed Signal)
Ignition Module
DLA
Application Supplied
Speed Control Input
Operation Input Voltage:
0-1 Volts at Idle/9+ Volts at High Speed.
GCU
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