Oil Pressure Sensor: Description and Operation

PURPOSE
The fuel pump and engine oil pressure indicator switch has two functions, to indicate low engine oil pressure and to supply battery voltage to the fuel pump in the event the fuel pump relay fails.

OPERATION
The Powertrain Control Module (PCM) checks the engine oil pressure continuously. If the oil pressure switch indicates low oil pressure at any time, the PCM will send information through serial data to the instrument cluster to turn "ON" the "Low Oil Pressure" telltale.

The oil pressure portion of the switch has normally closed contacts that open on an increasing oil pressure of 41 kPa (6 psi) or less, and close on a decreasing pressure of 14 (2 psi). When the switch is closed, the oil pressure signal is sent to the PCM, which in turn sends the information to the instrument cluster through serial data. The oil pressure lamp on the instrument cluster is then illuminated.

The fuel pump portion of the switch has a normally open contact that closes when increasing oil pressure of 41 kPa (6 psi) or less, and opens when decreasing pressure of 14 (2 psi). In the event the fuel pump relay fails, battery voltage is supplied to the fuel pump through the closed contacts from the switch.