Oil Pressure Gauge

The magnetic fields of the 0 psi and the 80 psi coils moves the pointer of the oil pressure gauge. The 2 coils are oriented at right angles so that the magnetic fields interfere with each other. Battery voltage is available from the GAUGES Fuse 4 through the CKT 39 (PNK) wire to the instrument cluster when the ignition switch is in the RUN or START position. If there is little current through the 80 psi coil, current flows through the 0 psi coil, placing the pointer at 0 psi. If the current though 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 2 paths to ground. Some of the current can pass through the fixed resistance of the 80 psi coil to Ground G101 through the CKT 451 (BLK/WHT) wire. The rest of the current will go to ground through the variable resistance of the oil pressure sensing element. The oil pressure sensing in the fuel pump switch and oil pressure gauge sensor produces a resistance of approximately 0 ohm when the oil pressure is 0 and 88 ohm at 80 psi. Most current passes through the oil pressure sensing element and not the 80 psi coil with the low resistance. If the oil pressure is high, the following conditions occur:
^ More current flows through the 80 psi coil
^ The pointer moves toward 80 psi

The CHECK GAUGES lamp lights when a low oil pressure condition occurs. The setpoint is 9.6 ohm or 5 psi.

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