Oil Pressure Warning Lamp/Indicator: Description and Operation

A red warning indicator glow when the oil pressure is below a prescribed valve. The indicator should come on when the ignition switch is first turned to the Run position. The indicator should go out within a few seconds after the engines starts, indicating that oil pressure is satisfactory.
The oil switch is calibrated to close between 4.5-7.5 psi. The indicator is connect between the oil pressure switch unit (mounted on the engine) and the coil terminal of the ignition switch.
On some vehicles only one warning indicator serving both the oil pressure switch and the temperature switch. These combined systems are identified by the word ENGINE on the warning indicator.