3508B Engine for Caterpillar Built Machines Caterpillar

Oil pressure is monitored by the oil pressure sensor. The oil pressure sensor is located on the filter outlet elbow on the front left corner of the engine. The 5.0 ± 0.2 VDC operating voltage for this sensor is supplied by the Electronic Control Module (ECM). The output of the oil pressure sensor is a 0.95 to 4.40 volts DC signal. The signal voltage is dependent upon the oil pressure. The voltage is interpreted by the ECM as oil pressure. The ECM compares the actual engine oil pressure to an oil pressure map. The map is stored in the ECM memory. The map represents the minimum acceptable oil pressure. The map is based upon engine speed. If the oil pressure drops below the minimum acceptable level, the ECM will activate the low oil pressure warning. The warning is sent to the monitoring system via the data link. This warning will be displayed on the monitoring panel. Also, an event will be logged in the ECM memory. Factory passwords are required to clear logged events. If the oil pressure rises above the reset line that is shown in Illustration 1, the warning will deactivate.

Illustration 1	g01035867
Oil pressure map

The ECM will generate a low oil pressure warning when the following conditions are met:

• The diagnostic codes for the oil pressure sensor are not active.

• The engine has been running for at least ten seconds. This ten second delay starts once the speed is within 50 rpm of low idle. This delay allows time for the oil pressure to build up after the engine has started. This delay also allows time for the oil pressure to build up after the engine oil and the filter have been changed.

• Pressure is below the trip line for low oil pressure for two seconds.