Oil Pressure Gauge

The pointer of the Oil Pressure Gauge is moved by the magnetic fields of two coils, the 0 psi Coil and the 80 psi Coil. The two coils are oriented at right angles so that the magnetic fields interfere with each other. Battery voltage is available from GAUGES Fuse 4 through the PNK (39) wire to the Instrument Cluster when the Ignition Switch is in RUN or START. Current flows through the 0 psi Coil which places the pointer at 0 psi if there is little current through the 80 psi Coil. If the current through the 80 psi Coil is high, then the pointer moves toward the 80 psi indication.

The current that passes through the 0 psi Coil has two paths to ground. Some of the current can pass through the fixed resistance of the 80 psi Coil and to Ground G101 through the BLK/WHT (451) wire. The rest of the current will go to ground through the variable resistance of the oil pressure sensing element. The oil pressure sensing element in the Fuel Pump Switch and Oil Pressure Gauge Sensor (Gas) or in the Engine Oil Pressure Indicator Sender (Diesel) produces a resistance of approximately 0 ohms when the oil pressure is zeroand 88 ohms at 80 psi. With this low resistance, most current passes through the oil pressure sensing element and not the 80 psi Coil. If the oil pressure is high, more current flows through the 80 psi Coil and the pointer moves to 80 psi.

A low oil pressure condition causes the CHECK GAUGES lamp to light. The setpoint is at approximately 9.6 ohms or 5 psi.

The Oil Pressure Gauge's accuracy is adequate for normal operator usage in that it provides a reasonably accurate indication of engine oil pressure from which sudden or long term changes may be identified. The sensing element's response is essentially linear over the operating range. The gauge accuracy specification is for 3.5 degrees (angular) at 0 psi and for 7 degrees at 80 psi. Gauge accuracy is not affected by changes in battery voltage.