TM 1-1740-221-13&P&P
FIELD MAINTENANCE
OIL PRESSURE SWITCHES
INITIAL SETUP:
Personnel Required
Test Equipment
91B, Light Wheel Vehicle Mechanic
Multimeter (, )
References
Tools and Special Tools
General Mechanic Tool Box (WP 0157, Item 24)
Materials/Parts
Equipment Condition
Tape, Anti-seize (WP 0156, Item 50)
Engine Shut Down and Cool
TEST/INSPECTION
NOTE
Inspect oil pressure switches for mounting security (no leaks) wiring for security, corrosion and
any damage affecting serviceability.
Pressure Switch Continuity Tests
WARNING
Eye protection required when applying air pressure to switches.
NOTE
To properly test pressure switches, removal of switch assembly is required.
1.
Oil Pressure Switch (Warning Light) Remove switch (Figure 1, Item 1) and ohms check for continuity
(normally closed) from the terminal connection to the switch case threads. Apply air pressure to the switch and
ohms check for loss of continuity (switch open). If switch fails either test, replace defective switch.
2.
Oil Pressure Switch (Hour Meter) Remove switch (Figure 2, Item 1) and ohms check (no continuity, normally
open) across the two electrical terminals. Apply air pressure and ohms check for continuity (pressure closes).
If switch fails either test, replace defective switch.
END OF TASK
REMOVAL
OIL PRESSURE SWITCH (WARNING LIGHT)
1. Disconnect battery negative cables (WP 0111).
2. Open engine cover (WP 0028).
NOTE
Label or tag all wiring terminals after removal to aid with switch reinstallation.
3.
Remove mount screw (Figure 1, Item 3).
4.
Remove wire 30 (Figure 1, Item 2).
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