Circuit DescriptionThe oil pressure switch is used by the engine control module (ECM) to detect the presence oflubricating oil pressure. Component LocationThe oil pressure switch is located on the engine block, below and to the right of the ECM. Shop Talk1) Confirm that the oil pressure sensor supply voltage is between (+) 4.5 and 5.25-VDC atthe sensor.2) Verify, with the driver, the engine speed at which the fault occurs. If the engine is beingoperated at too low of a speed under load, the oil pressure can drop below the engineprotection limits.3) Connect a manual gauge to monitor the actual oil...

Circuit DescriptionThe coolant temperature sensor is used by the ECM to monitor the temperature of the enginecoolant. The coolant temperature is used by the ECM for the engine protection system, timing,and fueling control. Component LocationThe coolant temperature sensor is located to the front of the thermostat housing. Shop TalkThe sensor reading will match to the following table if the sensor is functioning properly. Cummins ISB CM550 (1990-94) Fault Code: 143-SW PID: 100 SPN: 100 FMI: 1 Oil Pressure Switch Circuit Cummins ISB CM550 (1990-94) Fault Code: 143-SN PID: 100 SPN: 100 FMI: 1 Oil Pressure Switch Circuit Cummins ISB CM550...

Circuit DescriptionThe coolant temperature sensor is used by the ECM to monitor the temperature of the enginecoolant. The coolant temperature is used by the ECM for the engine protection system, timing,and fueling control. Component LocationThe coolant temperature sensor is located to the front of the thermostat housing. Shop TalkThe sensor reading will match to the following table if the sensor is functioning properly. Cummins ISB CM550 (1990-94) Fault Code: 144 PID: 110 SPN: 110 FMI: 3 Coolant Temperature Sensor Circuit Cummins ISB CM550 (1990-94) Fault Code: 143-SW PID: 100 SPN: 100 FMI: 1 Oil Pressure Switch Circuit Cummins ISB CM550...

Circuit DescriptionThe coolant temperature sensor is used by the ECM to monitor the temperature of the enginecoolant. The coolant temperature is used by the ECM for the engine protection system, timing,and fueling control. Component LocationThe coolant temperature sensor is located toward the front of the thermostat housing. Shop TalkThe sensor resistance reading will match the following table if the sensor is functioningproperly. Cummins ISB CM550 (1990-94) Fault Code: 144 PID: 110 SPN: 110 FMI: 4 Coolant Temperature Sensor Circuit Cummins ISB CM550 (1990-94) Fault Code: 144 PID: 110 SPN: 110 FMI: 3 Coolant Temperature Sensor Circuit Cummins ISB CM550 (1990-94)...

Circuit DescriptionThe coolant temperature sensor is used by the ECM to monitor the temperature of the enginecoolant. The coolant temperature is used by the ECM for the engine protection system, timing,and fueling control. Component LocationThe coolant temperature sensor is located toward the front of the thermostat housing. Shop TalkThe sensor resistance reading will match the following table if the sensor is functioningproperly. Cummins ISB CM550 (1990-94) Fault Code: 145 PID: 110 SPN: 110 FMI: 3 Engine Coolant Temperature 1 Sensor Circuit – Voltage Below Normal or Shorted to Low Source Cummins ISB CM550 (1990-94) Fault Code: 144 PID: 110 SPN:...