HYDRAULIC OIL TEMPERATURE
ENGINE COOLING WATER TEMPERA-
TURE
SWITCH TEST (See Figure 10G-21)
The temperature switch is a normally OPEN (NO) switch.
When the cooling water reaches 230°F (110°C) the
switch will close.
FIELD TEST
Using a jumper wire, remove the GRN wire and ground
it. Turn the ignition switch ON.
• An audible horn and the engine water temperature
light comes on, proceed with switch test, Step 1.
• Horn and/or engine water temperature light does
not come on. Check circuit wiring and/or bulb.
SWITCH TEST
1. Using a suitable container, fill it with engine or
hydraulic oil.
2. Heat the oil to 230°F (110°C).
3. Set multimeter to 200 Ω (ohms) scale.
4. Connect test leads as shown.
•
There should be no continuity through switch.
5. Slowly emerge switch into the heated oil.
•
Switch contacts should close, there should be a
reading of 0–0.5 Ω (ohms).
Replace a switch that does not meet all the above
test results or has resistance of 0.5 Ω (ohms) or more.
ELECTRICAL SYSTEM
SECTION 10G. SWITCHES
10G-21
10G
Figure 10G-21. Engine Cooling Water Temperature Switch Test
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