Operation CHARM: Car repair manuals for everyone.

11BD00


The control deviation during rail pressure regulation via the pressure regulator valve is too high.


Possible cause:

- Y74 (Pressure control valve)
Affected functions:

- Power generation

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Test 1: Rail pressure monitoring via pressure control valve

1. Rail pressure monitoring via pressure control valve

Test 1.1: Fuel tank level ?

Test 1.2: Test of low pressure circuit

Test 1.3: Check component Y74 (Pressure control valve).

1.1. Fuel tank level ?
Possible cause and remedy

- Fuel tank level minimum:5Liters
End of test

1.2. Test of low pressure circuit
Warning!Risk of explosion, poisoning and injury!Fuels are highly inflammable and toxic if inhaled. Fuels may cause skin damage. fuel vapors are explosive, invisible and spread out at floor level, they are toxic if inhaled and produce giddiness and an anaesthetizing effect.Rules of conduct and protective measures

- Wear suitable protective clothing.
- Pay attention to national safety precautions and regulations.
- No fire, sparks, naked flames and smoking.
- Ensure the work place is adequately ventilated.
- Never drain or pour in fuels over assembly pits.
- Store drained fuel in a suitable and sealed vessel.
- Immediately eliminate any fuel which has flowed out.
First-aid measures

- Clean moistened skin with water and soap.
- Change moistened clothing as quickly as possible.
- If fuel gets into your eyes, rinse out your eyes immediately with water and contact a doctor if necessary.


Please check the fault freeze frame data.
Question:How high was the tank fill level when the fault occurred?Question:Read fault memory once again.

YES

1.2. No further information available.


NO
Question:Was the tank fill level > 10 l ?

YES
Test prerequisites:Tank fill level is > 10 l.Type of fuel (Diesel)The low pressure fuel circuit has no external leaks.Continue with button F2

Test pressure in fuel low pressure circuit.
Figure legend

- 043Pressure measuring device0-10 bar(103 589 00 21 01)
- aT-piece for pressure test upstream of fuel filter(A 620 990 03 70)
- bT-piece for pressure test downstream of fuel filter(A 673 990 03 70)

- Shop-make test lines as shown in picture.
- This test can also be carried out alternatively with a commercially available pressure-vacuum tester with an appropriate test connector.
- Hydraulic clutch: see Workshop Equipment Manual WH58.30-Z-1054-13A







Test fuel pressure at fuel filter inlet.
Special tool

- 043Pressure measuring device0-10 bar(103 589 00 21 01)
Figure legend

- 043Pressure measuring device
- 70/1Inlet at fuel filter
IMPORTANT NOTE

- Kinked or clogged fuel lines may result in fuel pressures of up to 8 bar.
- Fabricate your own hose lines with a diameter of 8 mm and 10 mm.
Test sequence

- Switch off ignition.
- Await run-on time.
- Connect test pressure gauge.[See fig.]
- Start and run engine at idle speed for approx. 15 s.
Communication with ECU required







NO
End of test

1.3. Check component Y74 (Pressure control valve).
Test prerequisite

- Operate engine at idling speed.
- Fuel temp. of > 20°
- Carry out the test within 30 s.
Status of relevant actual value:
- Pressure control valve:Warning! Communication with ECU required.

- Fuel temperature:Warning! Communication with ECU required.
Specified value

- On/off ratio:<30%
- Fuel temp. of > 20°
Question

- Is the actual value o.k.?


YES
The actual value is okay.Possible cause and remedy

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

NO
Test signal voltage of component Y74 (Pressure control valve).
Figure legend

- Y74 (Pressure control valve)
Special tool

- Adapter cable220 589 00 99 35
Test prerequisite

- Operate engine at idling speed.
- Fuel temp. of > 20°
- Carry out the test within 30 s.
Test sequence

- Switch off ignition.
- Detach coupling at component Y74 (Pressure control valve).
- Connect adapter cable no. 220 589 00 99 35 to engine wiring harness Y74 (Pressure control valve).
- Measure direct voltage with multimeter between sockets (Y74/x1) 1 and (Y74/x1) 2
Specified value

- Voltage[1,7...2,0] V
Question

- Is the measurement value OK?







YES
Test current consumption of component Y74 (Pressure control valve).
Figure legend

- Y74 (Pressure control valve)
Special tool

- Adapter cable220 589 00 99 35
Test sequence

- Switch off ignition.
- Detach coupling at component Y74 (Pressure control valve).
- Connect adapter cable no. 220 589 00 99 35 to engine wiring harness Y74 (Pressure control valve).
- Operate engine at idling speed.
- Measure direct current with multimeter between sockets (Y74/x1) 1 and (Y74/x1) 2
Specified value

- Current[650...700] mA ca.4sec.
Question

- Is the measurement value OK?







YES
The measurement value is OK.Possible cause and remedy

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

NO
Check internal resistance of component Y74 (Pressure control valve).
Figure legend

- Y74 (Pressure control valve)
Special tool

- Adapter cable220 589 00 99 35
Test sequence

- Switch off ignition.
- Detach coupling at component Y74 (Pressure control valve).
- Connect adapter cable no. 220 589 00 99 35 at component Y74 (Pressure control valve).
- Measure resistance with multimeter between sockets (Y74) 1 and (Y74) 2
Specified value

- Resistor[3 ... 5]ohms
Question

- Is the measurement value OK?







YES
The measurement value is OK.Possible cause and remedy

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
- Test wiring from component N3/9 (CDI control unit) to component Y74 (Pressure control valve) with an ohmmeter for short circuit (positive or negative) and repair, if necessary.
End of test

NO
The measurement value is not OK.Possible cause and remedy

- Replace component Y74 (Pressure control valve).
Note

- After replacing the pressure regulator valve, the teach-in process for this component must be performed via menu 'Control unit adaptations'.
End of test

NO
The measurement value is OK.Possible cause and remedy

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test