Governor System
68
62 690 05 Rev. E
KohlerEngines.com
FIELD INSTALLED UPDATED DESIGN 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, GCU will
command DLA to perform homing
sequence. Throttle closes then returns
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)
Loss of ECU Speed
Output (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 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 will be below 1500
RPM.
Using EFI Diagnostic
Software, observe TPS
value for movement, 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 70 for
more information)
Rapid hunting and/or
surging
Rev-limiting feature
active. (ECU
controlled limitation)
If maximum RPM limit (4500 RPM +) is
exceeded, ECU suppresses injection
signals, cutting off fuel fl ow. This
process repeats itself in rapid
succession, limiting operation to preset
maximum.
See rows 1 and 2, view
throttle position, observe
for movement. Test DLA
function using stepper
motor controller tool. Refer
to Tools and Aids.
