Generac Power Systems GP Series Diagnostic Repair Manual page 49

Remove the oil pressure gauge and reinstall the oil
5.
pressure switch. Do NOT connect Wire 566 or Wire
14C to the switch terminals.
a. Set a DMM to measure resistance.
b. Connect the DMM test leads across the OPS
switch terminals. With the engine shut down,
the DMM should indicate INFINITY. If
CONTINUITY was measured, replace the OPS
switch.
c. With the DMM still connected to the OPS
switch, set the AUTO-OFF-MANUAL switch
MANUAL. The DMM should indicate
CONTINUITY after the engine has had a
chance to build pressure.
Set the DMM to measure DC voltage.
6.
a. Disconnect Wire 14C at the OPS.
b. Connect the black meter lead to a good
ground, and the red meter lead to Wire 14C.
Approximately 12 VDC should be measured. If
12 VDC is not measured, go to Step 7 and
check continuity on Wire 14C from the OPS
switch back to the main power relay (MPR)
Wire 14C.
Set the DMM to measure resistance.
7.
a. Disconnect Wire 14C from the MPR and
disconnect Wire 14C and Wire 566 from the
OPS switch.
b. Connect one meter lead to the disconnected
MPR Wire 14C and connect the other meter
lead to Wire 14C of the OPS. The DMM should
indicate CONTINUITY. If CONTINUITY was
not measured repair or replace as needed.
Set the DMM to measure resistance.
8.
a. Disconnect the ECM harness connector and
disconnect Wire 566 from the OPS switch.
b. Connect one meter lead to the ECM Pin 4C
and connect the other meter lead to Wire 566
of the OPS. The DMM should indicate
CONTINUITY. If CONTINUITY was not
measured repair or replace as needed.
Results
If the switch operated normally and proper oil pres-
1.
sure was measured, and Wires 566 and 14C
tested good, and/or the generator still shows an
error for oil pressure, replace the ECM.
Test 20 – Test Engine Function
Procedure
Remove front cover assembly.
1.
Remove spark plug from unit.
2.
Attempt to turn engine over by hand.
3.
Visually inspect for obstructions that would cause
4.
binding of the recoil once installed.
Diagnostic Repair Manual
Section 5 Engine Diagnostic Tests
Results
If engine cannot turn over freely with spark plug
1.
removed, either:
a. the engine has suffered an internal failure and
seized,
b. and/or the alternator end has seized.
Disconnect engine from alternator end and retest.
2.
Refer to flow chart.
3.
Test 21 – Test Engine Battery
Charging Circuit
General Theory
The battery is constantly being charged during the
operation of the generator. The engine stator, located
under the flywheel, has two yellow wires that lead to its
regulator/rectifier. DC voltage is delivered to the battery
via a red wire with each circuit/system. See Wiring
Diagram for greater detail.
Procedure/Results
NOTE: Check battery condition with a conductance
tester prior to conducting the following test. Battery
should be fully charged and its condition should be
greater than 65%.
NOTE: Refer to the specific wiring diagram for proper
component and wire identification.
NOTE: Engine will be running during each test.
Start engine and let run for a few minutes. Measure
1.
voltage on battery positive and negative terminals.
Shut engine off.
a. If voltage measured greater than 12.6 VDC,
stop testing and refer back to the flowchart.
Charging circuit is good.
b. If voltage measured greater than 12.6 volts,
and battery condition is good, go to Step 6.
c. If voltage measured less than 12.6 VDC,
proceed to Step 3.
Set DMM to measure AC volts and check for
2.
voltage on two yellow wires coming from the
engine stator coil.
a. If voltage measured less than 18 VAC, repair
wire/terminal if compromised or replace the
CHARGE COIL.
b. If voltage measured greater than 18 VAC, go to
Step 4.
Set DMM to measure DC volts and check for
3.
voltage on the red wire coming from the voltage
regulator/rectifier.
a. If voltage measured less than 12.5 VDC, and
battery is fully charged, replace the voltage
regulator/rectifier.
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