Turn the ignition key ON.

With the engine off, all users off and the accelerator pedal not operated, the oil pressure should be about 1 bar.

With the engine revolutions approximately 4000 rpm, the oil pressure should be between 3 and 3.5 bars.

The test can be considered over

Turn the ignition key OFF.

Disconnect the wiring harness connector from engine control unit connector B and the low engine oil pressure sensor (switch).

Turn the ignition key ON.

Measure the voltage between Pin 5 (wiring side) of the control unit and earth, checking that it is less than 0.3 V

See M010 ENGINE MANAGEMENT ECU

Repair or if necessary replace the electrical wiring between the engine control unit and the low engine oil pressure switch

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Turn the ignition key OFF.

Measure the resistance between Pin 5 (wiring side) of the control unit and earth, checking that it is more than 500 kOhm

See M010 ENGINE MANAGEMENT ECU

Repair or if necessary replace the electrical wiring between the engine control unit and the low engine oil pressure switch

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Measure the resistance between control unit Pin 5 (wiring side) and sensor Pin 1, checking it is less than 5 Ohms

See M010 ENGINE MANAGEMENT ECU

See K030 LOW ENGINE OIL PRESSURE SENSOR (SWITCH)

See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT

Repair or if necessary replace the electrical wiring between the engine control unit and the low engine oil pressure switch

Replace the minimum engine oil pressure switch.

Op. 1084A42 ENGINE OIL PRESSURE WARNING LIGHT SWITCH - R + R

and check the fault has disappeared

Restore the original swtich and replace the engine management control unit

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