Check operation of main engine control unit relay
- Make
- Fiat
- Model
- 500 Factory Service Manual
- Year
- 2007–2024
- Section
- Diesel injection system › Check operation of main engine control unit relay
CHECK OPERATION OF MAIN ENGINE CONTROL UNIT RELAY
| STEP | CHECK TO BE PERFORMED | RESOLUTION IF THE CHECK IS NOT OK |
|---|---|---|
| 1 | Turn the ignition key OFF. Turn off all the electrical users. In the engine compartment junction unit, remove relay T7 (first from the top in the the left lower row) Measure the voltage between Pin 30 of the base unit for relay T7 and the earth, ensuring it is greater than 11 V. Move on to Step 13 | Move on to Step 2 |
| 2 | Remove fuse F27 (fourth from the top in the left row) in the engine compartment junction unit and check it has not blown. | Repair or if necessary replace the electrical wiring between the battery positive and the engine compartment junction unit |
| 3 | Fit a new fuse F27 and check it does not blow. | Repair or if necessary replace the electrical wiring between the engine compartment junction unit and the engine control unit |
| 4 | Connect a shunt cable with a fuse across pin 87 of the base unit for relay T7 and the battery positive, checking that it has not blown. Move on to Step 10 | Move on to Step 5 |
| 5 | Disconnect the wiring harness connector from glow plug preheating control unit C. Fit a new fuse in the shunt connection and check it does not cut out. | Replace the glow plug preheating control unit |
| 6 | In the engine bay junction unit, remove relay T8 from the base (it is the first from the bottom in the right lower row). Fit a new fuse in the shunt connection and check it does not cut out. | Replace the fuel pump relay |
| 7 | Disconnect the cable loom connector from the engine management control unit connector A. Fit a new fuse in the shunt connection and check it does not cut out. | Replace the engine management control unit |
| 8 | Disconnect the wiring harness connection for the water in the filter sensor. Fit a new fuse in the shunt connection and check it does not cut out. | Replace the water presence sensor Op. 1060G30 |
| 9 | Repair or if necessary replace the wiring between engine control unit and the various disconnected electrical components. See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over | |
| 10 | Do not disconnect the shunt connection with fuse. Disconnect the cable loom connector from the engine management control unit connector A. Connect a shunt cable without a fuse between control unit Pin 80 (wiring side) See M010 ENGINE MANAGEMENT ECU and eath, checking that the fuse of the other shunt connection does not blow | Replace the fuel pump relay |
| 11 | Do not disconnect the shunt connection with fuse. Disconnect the shunt connection without fuse. Connect a shunt cable without a fuse across control unit Pin 76 (wiring side) See M010 ENGINE MANAGEMENT ECU and earth, checking that the fuse of the other shunt connection does not blow | Replace the ignition-operated relay |
| 12 | 12 Replace the main relay. The test can be considered over | |
| 13 | Measure the voltage between Pin 86 of the base unit for relay T7 and the earth, ensuring it is greater than 11 V. | Repair the engine compartment junction unit wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT If necessary, replace it Op. 5505A13 |
| 14 | Turn the ignition key ON. Measure the voltage between Pin 85 of the base unit for relay T7 and the earth, ensuring it is less than 0.3 V. Move on to Step 16 | Move on to Step 15 |
| 15 | If faults are found, restore the wiring between the engine compartment junction unit and the engine compartment junction unit See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT Replace the wiring if necessary The test can be considered over | Replace the engine management control unit |
| 16 | Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is less than 1.0 V. Move on to Step 35 | Move on to Step 17 |
| 17 | Turn the ignition key OFF. Disconnect the wiring harness connector from glow plug preheating control unit C. Turn the ignition key ON. Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is greater than 1.0 V. | Replace the glow plug preheating control unit |
| 18 | Turn the ignition key OFF. In the engine compartment junction unit, remove fuse F27 (fourth from the top in the left row) Turn the ignition key ON. Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is less than 1.0 V. Move on to Step 30 | Move on to Step 19 |
| 19 | Turn the ignition key OFF. Disconnect the wiring harness connection for the water in the filter sensor. Turn the ignition key ON. Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is less than 1.0 V. Move on to Step 27 | Move on to Step 20 |
| 20 | Turn the ignition key OFF. In the engine bay junction unit, remove relay T8 from the base (it is the first from the bottom in the right lower row). Turn the ignition key ON. Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is less than 1.0 V. Move on to Step 25 | Move on to Step 21 |
| 21 | Turn the ignition key OFF. In the engine bay junction unit, remove relay T6 from the base (it is the first from the bottom in the middle row). Turn the ignition key ON. Measure the voltage between Pin 87 of the base unit for relay T7 and the earth, ensuring it is less than 1.0 V. Move on to Step 23 | Move on to Step 22 |
| 22 | If faults are present, repair or if necessary replace the electrical wiring between the engine control unit and the various disconnected components. See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over | Replace the engine management control unit |
| 23 | Measure the voltage between Pin 85 of the base unit for relay T6 and the earth, ensuring it is less than 0.3 V. | Move on to Step 15 |
| 24 | Replace the injector. The test is complete | |
| 25 | Measure the voltage between Pin 85 of the base unit for relay T8 and the earth, ensuring it is less than 0.3 V. | Move on to Step 15 |
| 26 | Replace the fuel pump relay. The test may be considered over | |
| 27 | Check that the voltage across pin 1 of the control unit See K100 TEMPERATURE SENSOR AND HEATING RESISTANCE and the earth is greater than 0.3 V. Move on to Step 29 | Move on to Step 28 |
| 28 | If faults are present, repair or if necessary replace the electrical wiring between the engine control unit and the water presence sensor See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over | Replace the engine management control unit |
| 29 | Replace the water presence sensor Op. 1060G30 The test can be considered over | |
| 30 | Turn the ignition key OFF. Disconnect the wiring harness connector from the EGR solenoid Turn the ignition key ON. Check the voltage between the inlet contact of fuse F27 and earth. Ensure it is greater than 0.3 V. Move on to Step 32 | Move on to Step 31 |
| 31 | If faults are present, repair or if necessary replace the electrical wiring between the engine control unit and the EGR solenoid. See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over | Replace the engine management control unit |
| 32 | Turn the ignition key OFF. Disconnect the wiring harness connector from the turbine variable geometry solenoid. Turn the ignition key ON. Check the voltage between the inlet contact of fuse F27 and earth. Ensure it is greater than 0.3 V. Move on to Step 34 | Move on to Step 33 |
| 33 | If faults are present, repair or if necessary replace the electrical wiring between the engine control unit and the turbine variable geometry control solenoid. See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT The test can be considered over | Replace the engine management control unit |
| 34 | Turn the ignition key OFF. Disconnect the wiring harness connector from engine control unit connector B Turn the ignition key ON. Check the voltage between the inlet contact of fuse F27 and earth. Ensure it is less than 0.3 V. Move on to Step 33 | Repair or if necessary replace the electrical wiring between the engine compartment junction unit, EGR solenoid and the engine compartment junction unit |
| 35 | Turn the ignition key OFF. Disconnect the cable loom connector from the engine management control unit connector A. Check the resistance between Pin 85 of the base unit for relay T7 and the earth is greater than 500 kOhms. | Repair or if necessary replace the electrical wiring between the engine compartment junction unit and the engine control unit |
| 36 | Check that the resistance across Pin 85 of the base of relay T7 and Pin 80 (wiring side) of the control unit See M010 ENGINE MANAGEMENT ECU is less than 5 Ohms | Repair or if necessary replace the electrical wiring between the engine compartment junction unit and the engine control unit |
| 37 | Check that the resistance across Pin 87 of the base of relay T7 and Pin 4 (wiring side) of the control unit See M010 ENGINE MANAGEMENT ECU is less than 5 Ohms | Repair or if necessary replace the electrical wiring between the engine compartment junction unit and the engine control unit |
| 38 | Check that the resistance across Pin 87 of the base of relay T7 and Pin 6 (wiring side) of the control unit See M010 ENGINE MANAGEMENT ECU is less than 5 Ohms | Repair or if necessary replace the electrical wiring between the engine compartment junction unit and the engine control unit |
| 39 | Refit relay T7 in the base unit. Connect a shunt cable without a fuse across control unit Pin 80 (wiring side) and earth. Check that the voltage across control unit sensor Pin 4 (wiring side) See M010 ENGINE MANAGEMENT ECU and the earth is greater than 11 V. | Replace the main relay |
| 40 | Replace the engine management control unit |
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