Start the engine, allow to warm up and adjust to idle speed.

Turn off all the electrical users.

Turn off all the cooling fans.

Check that the coolant temperature reading on the diagnostic instrument is more or less the same as the temperature shown on the instrument panel.

The test can be considered over

Turn the ignition key OFF.

Disconnect the wiring harness connector from the engine temperature sending unit

See K036 ENGINE COOLANT TEMPERATURE SENSOR/SENDER UNIT

Turn the ignition key ON.

Measure the voltage between Pin 2 of the sending unit and Earth, checking it is within a range between 4.8 and 5.2 V.

See K036 ENGINE COOLANT TEMPERATURE SENSOR/SENDER UNIT

Move on to Step 4

If faults are present, repair or if necessary replace the electrical wiring between the engine control unit and the temperature sending unit.

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

The test can be considered over

Replace the engine management control unit

Op. 1060G80 DIESEL ELECTRONIC INJECTION CONTROL UNIT - .R

Replace the engine management control unit

Op. 1060G80 DIESEL ELECTRONIC INJECTION CONTROL UNIT - .R

Connect a shunt cable fitted with a fuse between pins 1 and 2 of the sending unit

See K036 ENGINE COOLANT TEMPERATURE SENSOR/SENDER UNIT

Check that the reading for coolant temperature on the diagnostic instrument is greater than 0.1 V.

Move on to Step 3

Replace the coolant temperature sensor

Op. 1060G14 ENGINE COOLANT TEMPERATURE SENSOR - R.R.