Kohler COM7.5 Service Manual page 45

5.3 Control Board Tests
Use the troubleshooting procedures in Section 3 to
diagnose generator set and engine problems. If the
troubleshooting procedures indicate a problem with the
controller circuit board, use the tests in this section to
check the board.
Refer to the wiring diagrams in Section 7 when
troubleshooting the generator set control circuit board.
Circuit board components cannot be repaired or
replaced; if the troubleshooting process reveals a faulty
component on the circuit board, replace the board.
Note: Use an ohmmeter or continuity tester to check for
shorts or open leads in the wiring harnesses
before replacing the controller circuit board or
other system components.
Disconnect the generator system from the remote
control system at controller interface harness GM14245
and use the generator set master switch to operate the
generator set. If the generator set operates normally
when the controller interface harness is disconnected,
then the problem is with the remote control system.
Refer to the manufacturer's instructions for the remote
control system to troubleshoot the problem.
problem persists after the controller interface harness is
disconnected, use the troubleshooting procedures in
this manual to diagnose the problem.
WARNING
Hazardous voltage.
Can cause severe injury or death.
Only authorized personnel should
open the enclosure.
(600 volts and under)
WARNING
Hazardous voltage.
Can cause severe injury or death.
Operate the generator set only when
all guards and electrical enclosures
are in place.
Servicing the generator set when it is operating. Exposed
moving parts can cause severe injury or death. Keep
TP-6120 5/02
If the
Moving rotor.
hands, feet, hair, clothing, and test leads away from the belts
and pulleys when the generator set is running. Replace
guards, screens, and covers before operating the generator
set.
Short circuits. Hazardous voltage/current can cause
severe injury or death. Short circuits can cause bodily injury
and/or equipment damage.
connections with tools or jewelry while making adjustments or
repairs. Remove all jewelry before servicing the equipment.
5.3.1 Fuel Control Circuit
Move the generator set master switch to the START
position and check for 12 VDC to the fuel valve on lead
70. If the valve receives voltage but does not open,
replace the valve.
If there is no voltage to the valve, check wiring harness.
If the wiring harness is good but the fuel valve does not
receive voltage, replace the controller circuit board.
5.3.2 Speed Sensing and Governor
(Throttle Control) Circuits
The controller monitors the DC voltage from the voltage
rectifier to sense and control the engine speed. If the
engine speed varies erratically, test the governor
operation as described in Section 4.2. If the tests show
that the erratic operation is not caused by a faulty
governor, replace the controller circuit board.
5.3.3 Start Circuits
Move the generator set master switch to the START or
RUN position. If the engine does not crank, check the
following components:
1. Check the battery voltage. Recharge or replace a
weak or dead battery.
2. Check for 12 VDC to the starter motor. Also verify
that the starter motor is grounded. See Section 7,
Wiring Diagrams. If the starter motor is receiving
voltage but not functioning, replace it. If there is no
voltage to the starter motor, check the harness and
connections and then proceed to step 3 to check
the starter (crank) relay.
3. Check for 12 VDC to the crank relay.
Section 7, Wiring Diagrams. If the crank relay is
receiving voltage but not functioning, replace it. If
there is no voltage to the crank relay, check the
harness and connections.
4. Check for 12 VDC from the control board on pin
P2-1 (lead 71). If there is no voltage, replace the
controller circuit board.
Section 5 Controller Operation and Test
Do not contact electrical
See
35