Service Manual

Part Numbers
114270
Purpose
This switch monitors vacuum in the air cleaner box to determine if the air
cleaner is plugged.
How It Works
The switch is turned on by a slight vacuum applied to the inlet. This is
accomplished by a small electrical contact that is connected to a
diaphragm inside the switch. Note: Switch comes with one female
crimp-on connector.
Testing
1. Verify that the hose is connected to the “vacuum” side of the switch.
(Notice that there is also a pressure side.)
2. Disconnect the wiring harness and the hose.
3. Verify that there is no continuity across the two terminals.
4. Connect a vacuum gauge to the switch and evacuate slightly. There
should be continuity.
Part Numbers
NN10274
Purpose
The engine temperature switch turns on an indicator light when the head
temperature reaches the temperature specified below.
How It Works
The contacts inside the switch are normally open. As the body of the
switch warms, the clearance between the contacts narrows, until the
switch closes at 320-340 degrees F. It does not reopen until the
temperature falls to 280-310 degrees F.
Testing
1. Remove the switch from the harness.
2. Using a VOM or a test light, check the circuit between the body of the
switch and the terminal. There should not be continuity at room
temperature.
3. The point at which the switch turns on can be tested by heating to
300 degrees F. Slowly raise the temperature of the switch, noting the
point at which the switch turns on. It should close between 320 and
340 degrees F. Keep track of the temperature as the switch cools and
note the point at which it again opens. It should open between 280
and 310 degrees F.
Switch
Air Cleaner
Pressure
Switch
Engine Temperature
Glossary
GLOSSARY
3-26 Demystification Guide