Cummins ISB CM550 (1990-94) Fault Code: 298 PID: 223 SPN: 1084 FMI: 4 OEM Pressure Sensor Circuit

Circuit Description
The OEM sensor signal is used by the electronic control module (ECM) to monitor the OEM
pressure. The OEM pressure is used by the ECM in one of two ways:1. The ECM can shut
down the engine based on an OEM pressure input value exceeding or falling below a
customer-specified value.2. The ECM can control a device (dual-output driver A and driver B)
based on the value of the OEM pressure.A sensor that has failed low can be caused by shorts to ground on the signal wire or an internally grounded (faulty) sensor.

Component Location
The location varies with the OEM. Refer to the OEM manual.

Shop Talk
The resistance of all pressure sensors varies with the pressure. Refer to the OEM
troubleshooting and repair manual for specifications.