REF: Service Procedures 30

Testing the Oil Pressure Switch

Testing for an Open Circuit

These were bench tested but can simulate conditions while installed with the signal wire removed.
This requires a multi-meter set for continuity with the buzzer.
The black probe below can alternately be placed against the engine.
With the engine shut off and the signal wire dis-connected, the contact points should be pressing against each other ensuring continuity.

Touch the probes on the same side of the switch to ensure you have
good contact points on the probes. Clean the area if needed.
Probe each side of the switch and the buzzer on the meter should
sound off thus ensuring continuity between the contacts. If not, the
switch is defective and has to be replaced.
This tested out to be defective with an open circuit. 1)

Testing for the Opening / Closing Pressure

This setup was made using regular plumbing and air hose fittings.
This requires a multi-meter set for continuity with the buzzer.

The valve was placed inline in case something went wrong. 2)
With zero pressure applied, the circuit is closed, continuity is achieved
between the probes and the buzzer sounds off. 3)
With 27 PSI applied, continuity is broken and the buzzer is quiet. 4)
This switch didn't make contact until the pressure got down to about 2-1/2 PSI.
However, this test should have been performed with a lower range gauge for tighter low end calibration. 5)

1) , 5)
photos by Hippysmack
2) , 3) , 4)
photo by Hippysmack
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