244000457 - D25 ENGINE DOES NOT SWITCH TO GAS

The engine starts normally in petrol mode but does not then switch to methane mode.
STEPOPERATIONS TO BE CARRIED OUTTEST RESULTS
0PRELIMINARY CHECKSALL OKPROBLEMS ENCOUNTEREDACTION
Check, first, for the presence of METHANE in the tank by checking methane pressure at the reduction unit intakeMove on to Step 1Pressure lower than 15 bar and methane level therefore too lowRestore correct methane level
1CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Connect the diagnostic equipment to the diagnostic connector and check the following at the petrol and METHANE engine management unit, in the errors ambient:

  • no errors in the petrol and METHANE management control unit
Move on to Step 2Error detected in the petrol engine management unitContinue following the instructions for the diagnostic equipment
Error detected in the METHANE engine management unitContinue following the instructions for the diagnostic equipment
No communication between the petrol engine management unit and METHANE engine management unitRestore connection between petrol and METHANE control unit    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
METHANE control unit not connected to earthRestore earth connection    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
2CHECK METHANE INJECTORSALL OKPROBLEMS ENCOUNTEREDACTION
Check methane injectors are operating correctly    See Test 1058A GAS CIRCUIT MULTI POINT INJECTIONMove on to Step 3Methane injectors defectiveReplace the injectors    Op. 1058A68 SET OF CNG INJECTION SYSTEM INJECTORS - R R WITH CNG MANIFOLD PIPE REMOVED INCLUDES GASKET REPLACEMENT
Injector control relay defectiveReplace the relay
3CHECK METHANE/PETROL SELECTION BUTTONALL OKPROBLEMS ENCOUNTEREDACTION
Keeping the Examiner diagnostic equipment connected to the diagnostic connector check the following at the engine control unit, in the parameters ambient :

  • correct operation of the METHANE/Petrol selector
Check operation of the METHANE/Petrol selector    See Test 1058O CNG SUPPLY TESTS
Move on to Step 4METHANE/PETROL selector defectiveReplace the switch    Op. 1058A20 CNG/METHANE SWITCH - R.R.
Wiring brokenRestore wiring    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
Selector power supply interruptedRestore wiring continuity    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
Methane control unit defectiveReplace METHANE control unit    Op. 1058A80 CNG INJECTION UNIT CONTROL UNIT - R R
4CHECK METHANEN PRESSURE SIGNALALL OKPROBLEMS ENCOUNTEREDACTION
Check the following, in order:

  • correct power supply to methane pressrue sensor;
  • the correct voltage signal for the methane level sensor to the methane control unit, by carrying out Test 1058AA
    See Test 1058A GAS CIRCUIT MULTI POINT INJECTION
Move on to Step 5Methane pressure sensor power supply incorrectRestore correct power supply    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
Pressure sensor defectiveReplace pressure sensor    Op. 1058A44 CNG/FUEL SWITCH - R R
5CHECK CAN LINE CONNECTING ENGINE MANAGEMENT CONTROL UNITALL OKPROBLEMS ENCOUNTEREDACTION
Check continuity/insulation of CAN line connecting petrol engine control unit and methane engine management unit    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENTEnd of diagnosisCAN line interruptedRestore continuity    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
CAN line short-circuitedRestore insulation    See E5032 METHANE ENGINE ELECTRONIC MANAGEMENT
Methane control unit defectiveReplace control unit    Op. 1058A80 CNG INJECTION UNIT CONTROL UNIT - R R
The engine starts normally in petrol mode but does not then switch to GAS mode.
STEPOPERATIONS TO BE CARRIED OUTTEST RESULTS
0PRELIMINARY CHECKSALL OKPROBLEMS ENCOUNTEREDACTION
Check, first of all, that there is LPG in the tankMove on to Step 1LPG level lowRestore correct LPG level
1CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Connect the diagnostic equipment to the diagnostic connector and check the following at the petrol and LPG engine management unit:

  • in the errors ambient no errors in the petrol and LPG management control units;
  • in the parameters ambient, the plausibility of all the parameters
Move on to Step 2Error detected in the petrol engine management unitContinue following the instructions for the diagnostic equipment
Error detected in the LPG engine management unitContinue following the instructions for the diagnostic equipment
No communication between the petrol engine management unit and LPG engine management unitRestore connection between petrol and LPG control unit    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
LPG control unit not connected to earthRestore earth connection    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
LPG pressure more than or equal to 20 barMove on to Step 6
2GAS/PETROL SELECTOR CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Keeping the Examiner diagnostic equipment connected to the diagnostic connector check the following at the engine control unit, in the parameters ambient :

  • correct operation of the GAS/Petrol selector.
Check the operation of the GAS/Petrol selector by carrying out Test 1057OA    See Test 1057O LGP SUPPLY TESTS
Move on to Step 3GAS/PETROL selector defectiveReplace the selector
Wiring brokenRestore wiring    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
Selector power supply interruptedRestore wiring continuity    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
LPG control unit defectiveReplace LPG control unit
3CHECK CAN LINE CONNECTING ENGINE MANAGEMENT CONTROL UNITALL OKPROBLEMS ENCOUNTEREDACTION
Check continuity/insulation of CAN line connecting petrol engine control unit and LPG engine management unit    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENTMove on to Step 4CAN line interruptedRestore continuity    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
CAN line short-circuitedRestore insulation    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
4LPG LEVEL SENSOR CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check the following, in order:

  • correct power supply to LPG level sensor;
  • the correct operation of the LPG level sensor, by carrying out Test 1043AE
    See Test 1043A GPL TANK
Move on to Step 5LPG level sensor power supply not correctRestore correct power supply    See E5031 LPG FUEL SYSTEM ELECTRONIC MANAGEMENT
LPG level sensor defectiveReplace the LPG level sensor
5CHECK LPG PRESSUREALL OKPROBLEMS ENCOUNTEREDACTION
Check the following, in order:

  • the correct operation of the LPG pressure sensor, by carrying out Test 1043BB;
  • the correct operation of the LPG return solenoid valve, by carrying out Test 1043BC;
  • the correct operation of the LPG pump, by carrying out Test 1043AA
    See Test 1043B GPL FUEL CIRCUIT PIPES    See Test 1043A GPL TANK
Move on to Step 6Pressure sensor defectiveReplace the sensor
Return solenoid defectiveReplace the solenoid valve
LPG pump defectiveReplace the LPG pump
6CHECK ON TANK FILLER RESTRICTER VALVE AND LPG LEVEL SENSOR FLOATALL OKPROBLEMS ENCOUNTEREDACTION
Disconnect the LPG tank, drain it, send it to the authorized service centre and check:

  • the correct operation of the tank filling restricter valve, by carrying out Test 1043AF;
  • the correct operation of the LPG level sensor, by carrying out Test 1043AE
    See Test 1043A GPL TANK
End of diagnosisFiller restricter valve faultyReplace the tank filler restricter valve
Level sensor float defectiveReplace the sensor