Oil Pressure Gauge

The magnetic fields of the 2 coils, the 0 kPa (0 psi) coil and the 551.6 kPa (80 psi) coil, move the pointer of the oil pressure gauge. The magnetic fields interfere with each other, because the 2 coils are at right angles. Battery voltage is available from GAUGES fuse 4 through CKT 39 (PNK) to the instrument cluster when the ignition switch is in the RUN position or in the START position. Current flows through the 0 kPa (0 psi) coil which places the pointer at 0 kPa (0 psi), when the 551.6 kPa (80 psi) coil has little current. When the current through the 551.6 kPa (80 psi) coil is high, the pointer moves toward the 551.6 kPa (80 psi) indication.

The current that passes through the 0 kPa (0 psi) coil has 2 paths to ground. Some of the current passes through the fixed resistance of the 551.6 kPa (80 psi) coil to ground G1O1 through CkT451 (BLK/WHT). The remainder of the current goes to ground through the variable resistance of the oil pressure sensing element. The oil pressure sensing element in the fuel pump switch and the oil pressure gauge sensor in gasoline vehicles or in the engine oil pressure indicator sender in diesel vehicles produces a resistance of approximately 0 ohm when the oil pressure is zero, and 88 ohm when the oil pressure is 551.6 kPa (80 psi). When the oil pressure is high, more current flows through the 551.6 kPa (80 psi) coil and the pointer moves to 551.6 kPa (80 psi).

The CHECK GAUGES lamp lights when a low oil pressure condition is present. The set point is at approximately 9.6 ohm or 34.5 kPa (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 which identifies sudden or long term changes. The sensing element's response is essentially linear over the operating range. The gauge accuracy specification is 3.5 degrees (angular) at 0 kPa (0 psi) and 7 degrees at 551.6 kPa (80 psi). Changes in battery voltage do not affect the gauge accuracy.