Fault-Tracing
Fault-tracing DEM-P188974
Checking the oil pressure
- Ignition on.
Read off the oil pressure in the Differential Electronic Module (DEM). The pressure must rise when the engine speed exceeds 500 rpm. Use VIDA Vehicle communication.
First read off the oil pressure with the ignition on and then with the engine running. At read out, the oil pressure must rise when the engine rpm exceeds 500 rpm, the pressure must rise immediately after the engine's rpm increases.
If the pressure does not rise, this means that a fault has occurred.
Does the pressure increase?
Yes - Information
No - Checking the component and wiring
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Fault-tracing information
Information
Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.
Do you want to exit fault-tracing?
Yes - Exit Fault-tracing
No - Attempt New Test
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Attempt New Test - Checking the oil pressure
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Information
Note! A mechanical fault in the AOC unit can be one possible cause of the trouble code being set. Therefore a first step should be to check the AOC unit for any damage or oil leaks. Listen also for noise from the clutch/back axle. Remedy as necessary.
Other information:
- Test driving Active on Demand Coupling, automatic transmission, TF-80SC AWD, AW50/51 AWD
- For replacement of the AOC unit see: Differential electronic module (DEM), replacement
Continue - Verification
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Checking the connectors and leads
- Ignition off
- Check the connector between the Differential Electronic Module (DEM) and the feed pump with respect to contact resistance and oxidation.
- Check the lead between the Differential Electronic Module (DEM) and the feed pump for damage.
- Engine idling.
Check the voltage by measuring with a voltmeter on the control module connector to the pump motor. Measure between #1 and #2.
Note! The voltage is a pulse width modulated signal which can vary considerably and is only measurable a short while.
Remedy as necessary.
Other information:
- For replacement of the AOC unit see: Differential electronic module (DEM), replacement
- Signal specification
- Oil pump active on demand coupling (AOC), replacing, TF-80SC AWD
- Differential electronic module (DEM), replacement
- Checking wiring and terminals Checking Wiring and Terminals
Continue - Information
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Verification
Verification
Hint: After carrying out the repair, check that the fault has been remedied.
Note! After the AOC unit has been repaired or replaced, a test drive is required to check that the fault has been remedied.
- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
Switch on the pump motor and check that it starts and runs normally.
Hint: The motor should hum and vibrate slightly. Listen with a screwdriver or stethoscope against the ear.
Other information:
- Test driving Active on Demand Coupling, automatic transmission, TF-80SC AWD, AW50/51 AWD
- Test driving Active on Demand Coupling, manual transmission, M66 AWD
Is the feed pump working?
Yes - Troubleshooting procedure complete
No - Fault-tracing information
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Checking the component and wiring
- Ignition off.
Check the connector for the Differential electronic module (DEM). Check for damage and loose connections.
Check that the cable harness is intact and not trapped or damaged.
Check that the oil pressure sensor (13) is correctly installed and that it does not have any external damage. Check that the oil pressure sensor oil ducts are intact and free of dirt.
Remedy as necessary.
If no fault is found, try a new pressure sensor.
Other information
- Checking wiring and terminals Checking Wiring and Terminals
- Temperature / pressure sensor active on demand coupling (AOC), replacing
Is the function OK?
Yes - Troubleshooting procedure complete
No - Checking the connectors and leads
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Information
- Ignition on.
Check status for relevant diagnostic trouble code.
No further corrective action is required if the diagnostic trouble code (DTC) is intermittent and does not recur.
If the DTC status is permanent, continue with fault tracing.
Do you wish to continue with fault tracing?
Yes - Checking the connectors and leads
No - FAULT FOUND
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