Oil Pressure

The oil pressure gauge indicates the pressure of the lubricating oil flow provided by the engine oil pump. The oil pressure gauge sending unit is a variable resistor that is mounted to the engine block. The sending unit senses the oil pressure in a main oil passage just downstream from the engine oil pump. When electric power is supplied to the gauge, current flows through the gauge to the resistor in the sending unit and then to the ground at the engine block. The position of the oil pressure gauge pointer is determined by the strength of the current flowing through the gauge.

When oil pressure is low, the following situations exist:
^ The resistance of the sending unit is low.
^ Current flow through the gauge is high.
^ The gauge indicator needle shows a low pressure reading.

As oil pressure increases, the following situations occur:
^ The resistance of the sending unit resistor increases.
^ Current flow through the gauge is reduced.

Under normal conditions the oil pressure reading should be measure 138-414 kPa (20-60 psi). Engine oil pressure should never fall below a reading of 28 kPa (4 psi), even at idle.