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SECTION 4.4
DIAGNOSTIC TESTS
Page 141
TEST 75 – CHECK OIL PRESSURE SWITCH
AND WIRE 86
DISCUSSION:
If the oil pressure switch contacts have failed in their
closed position, the engine will probably crank and
start. However, shutdown will then occur within about
5 (five) seconds. If the engine cranks and starts, then
shuts down almost immediately with a LOP fault light,
the cause may be one or more of the following:
• Lowengineoillevel.
• Lowoilpressure.
• Adefectiveoilpressureswitch.
PROCEDURE:
1. Navigate to the Digital inputs display screen.
a. Press “ESC” until the main menu is reached.
b. Press the right arrow key until “Debug” is flashing.
c. Press “Enter”.
d. Press the right arrow key until “Inputs” is flashing.
e. Press “Enter”.
DEBUG
INPUTS
INPUT 1
INPUTS 1 - 8:
1 0 1 1 0 0 0 1
Figure 41. The Home Page, Debug and Input Screens
f. Digital Input 1 is Wire 86 from the Low Oil
Pressure switch to the board. Refer to Figure 41.
g. Set the AUTO-OFF-MANUAL switch to the
MANUAL position.
h. Observe Input 1 for a change from "1" to "0". A
change from "1" to "0" indicates that the control
board sensed the LOP switch change states. If
the generator still shuts down, replace printed
circuit board.
i. If the input did not change states, proceed
to Step 2
2. Check engine crankcase oil level.
a. Check engine oil level.
b. If necessary, add the recommended oil to
the dipstick FULL mark. DO NOT OVERFILL
ABOVE THE FULL MARK.
3. With oil level correct, try starting the engine.
a. If engine still cranks and starts, but then shuts
down, go to Step 4.
b. If engine cranks and starts normally, discon-
tinue tests.
4. Do the following:
a. Disconnect Wire 86 and Wire 0 from the oil
pressure switch terminals. Remove the switch
and install an oil pressure gauge in its place.
b. Start the engine while observing the oil pres-
sure reading on gauge.
c. Note the oil pressure.
(1) Normal oil pressure is approximately 35-40
psi with engine running. If normal oil pres-
sure is indicated, go to Step 4 of this test.
(2) If oil pressure is below about 4.5 psi, shut
engine down immediately. A problem exists
in the engine lubrication system.
Note: The oil pressure switch is rated at 10 psi
for V-twin engines, and 8 psi for single cylinder
engines.
Figure 42. Oil Pressure Switch
5. Remove the oil pressure gauge and reinstall the oil
pressure switch. Do NOT connect Wire 86 or Wire 0 to
the switch terminals.
a. Set a VOM to measure resistance.
b. Connect the VOM test leads across the switch
terminals. With engine shut down, the meter
should read CONTINUITY. If INFINITY is
measured with the engine shutdown, replace
the LOP switch.
c. Crank and start the engine. The meter should
read INFINITY.
6. Set a VOM to measure resistance.
DC CONTROL
PART 4