Circuit Description
The coolant temperature sensor is used by the ECM to monitor the temperature of the engine
coolant. The coolant temperature is used by the ECM for the engine protection system, timing,
and fueling control.
Component Location
The coolant temperature sensor is located toward the front of the thermostat housing.
Shop Talk
The sensor resistance reading will match the following table if the sensor is functioning
properly.
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: 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) 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 (1990-94) Fault Code: 141-SW PID: 100 SPN: 100 FMI: 4 Oil Pressure Switch Circuit
