Mercury E4ZZ-9278-A Sender Assy - Oil Pressure

While oil pressure switches are used for vehicles with low oil pressure warning lamps, oil pressure senders are used for gauges. They are situated on the engine and can be tested by disconnecting the wire, attaching a jumper wire to the terminal, and grounding it. If this happens, replace the switch. Otherwise, try different grounding areas or touch the jumper wire to the negative battery post. The engine might not be properly grounded. Finally, if upon reconnecting the original wire into the ignition switch and turning it on, all other lights come on, then you have a defective switch that should be replaced. To remove and install, disconnect battery cable, wiring, remove sender/switch. Apply electrically conductive sealer to threads and tighten unit. Attach wiring and reconnect battery cable.