Cummins ISB CM550 (1990-94) Fault Code: 415-SW PID: 100 SPN: 100 FMI: 1 Oil Pressure – Engine Protection With An Oil Pressure Switch

Posted by PerDiezel Solutions on January 16, 2026

Circuit Description
The oil pressure switch is used by the electronic control module (ECM) to detect the presence
of lubricating oil pressure.

Component Location
The oil pressure switch is located on the engine block below the ECM.

Shop Talk
1) Verify, with the driver, the engine speed at which the fault occurs. If the engine is being
operated at too low of a speed, the oil pressure can drop below the engine protection
limits.
2) Connect a manual gauge to monitor actual oil pressure of the engine.
3) Engines in the field can have had a jumper harness kit installed which connects the oil
pressure switch to pin K in the 23-pin OEM connector or cavity 8 in the Ford OEM
connector.
4) The fault will trigger if lubricating oil pressure drops below 41 kPa [6 psi] for 30 seconds.

Engine Protection Shutdown will be activated after an additional 30 seconds if the feature
is enabled in the ECM.

Cummins ISB CM550 (1990-94) Fault Code: 415-SN PID: 100 SPN: 100 FMI: 1 Oil Pressure – Engine Protection

Cummins ISB CM550 (1990-94) Fault Code: 391 PID: SID 017 SPN: 632 FMI: 11 Fuel Pump Relay Coil Supply Circuit

Cummins ISB CM550 (1990-94) Fault Code: 387 PID: SID 232 SPN: FMI: 1 Accelerator Position Sensor Circuit

Cummins ISB CM550 (1990-94) Fault Code: 387 PID: 91 SPN: FMI: 1 Accelerator Position Sensor Circuit

Cummins ISB CM550 (1990-94) Fault Code: 387 PID: SID 232 SPN: FMI: 3 Accelerator Position Sensor Circuit

Cummins ISB CM550 (1990-94) Fault Code: 387 PID: 91 SPN: FMI: 3 Accelerator Position Sensor Circuit

WARNING!