Cummins ISB CM550 (1990-94) Fault Code: 141-SW PID: 100 SPN: 100 FMI: 4 Oil Pressure Switch Circuit

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

Component Location
The oil pressure switch is located on the engine block, below and to the right of the ECM.

Shop Talk
1) If Fault Code 143 or 415 is not present, the problem is not related to the engine
lubrication system.
2) Your diagnostic tool can be used to monitor the oil pressure signal voltage going into the ECM.
3) If an oil pressure switch is installed, INSITE™ will read a constant value of 379 kPa [55
psi] ±2 kPa [±0.3 psi] if the ECM is reading a signal from the oil pressue switch.
4) The switch is a single wire device which requires engine block ground for operation.
5) Engine Protection will activate, if enabled, if the lubricating oil pressure drops below 41
kPa [6 psi] with the engine running.