Although these components look different, they operate in the same way. To check that they are in good working order, remove them from their housing and, with a tester connected across the connector terminals, check for the following conditions:
When the switch is down (on), the tester reading must be "0".
When the switch is up (off), the tester must go to the end of the scale range. If the tester gives any other readings, the component concerned must be changed.
To test the oil pressure transmitter, connect one tester terminal to the single connector and earth the other terminal on the outer casing.