Generac Power Systems 941-2 Service Manual page 103

GENERAL
The engine mounts an Oil Pressure Switch (LOP) and
an Oil Temperature Switch (HTO). These two switch-
es, in conjunction with the A6060 circuit board, pro-
tect the engine against (a) low oil pressure and (b)
high oil temperature.
The engine protective circuit Is shown in Figure 1.
OIL PRESSURE SWITCH
DESCRIPTION:
The Oil Pressure Switch has normally-closed contacts
which are held open by engine oil pressure during
cranking and running. Should oil pressure drop below
approximately 5 psi, the switch contacts will close to
complete the Wire 85 circuit to ground. A6060 circuit
board action will then de-energize the Wire 14 circuit
and the engine will shut down.
The A6060 circuit board provides a time delay to
allow oil pressure to build during startup, to prevent
premature shutdown.
TESTING THE SWITCH:
Use a volt-ohm-milliammeter (VOM) to test the oil
pressure switch. Connect the VOM test leads across
the switch terminal and the switch body. With the
engine shut down, the meter should read "continuity"
(a very small resistance is acceptable). With engine
running, the meter should read "infinity".
OIL TEMPERATURE SWITCH
DESCRIPTION:
This thermostatic switch has normally-open contacts.
Should engine oil temperature exceed a preset safe
value (about 293° F.), the switch contacts will close.
On closure of the Switch contacts, the Wire 85 circuit
will be connected to frame ground. Engine shutdown
will then occur.
Figure 1. Engine Protective Circuit
SHUTDOWN FEATURES
Figure 2. Engine Protective Devices
Figure 3. Testing the Oil Temperature Switch
TESTING:
See Figure 3. Remove the switch and place its sens-
ing tip into oil. Place a thermometer Into the oil.
Connect the test leads of a VOM across the switch
terminals. The meter should read "Infinity". Heat the
oil. When oil temperature reaches approximately
287°-296° F. (142°-147° C.), the meter should read
"continuity" (a small resistance is acceptable).
Section 6.5
(continued)
Page 6.5-1