D138

The message from the auxiliary oil pump is not available on the CAN bus.


Possible cause:

- M42 (Electric transmission oil pump) / N89 (Transmission oil additional pump control unit)
Affected functions:

- Engine start

-------------------------------------------------

Test 1: Check component M42 (Electric transmission oil pump).

1. Check component M42 (Electric transmission oil pump).
Operation number of operation texts and work units or standard texts and flat rates:27-0641Test prerequisite

- Battery voltage is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N89 (Transmission oil additional pump control unit).
- Use multimeter to check voltage directly at jacks of wiring harness for component N89 (Transmission oil additional pump control unit).
- Switch on ignition.
Measure direct voltage with multimeter between 1 and 4Specified value

- Voltage [8,5...16,4] V
Question

- Is the measurement value OK?







YES
The measurement value is OK.Further test:Test CAN wiring for Open circuit.Test sequence

- Switch off ignition.
- Disconnect connector at component N89 (Transmission oil additional pump control unit).
- Expose component X30/21 (Drive train CAN voltage distributor connector).
CAN bus HighMeasure resistance with multimeter between (X30/21) 2 and (N89) 3CAN bus LowMeasure resistance with multimeter between (X30/21) 1 and (N89) 2Question

- Is there an open circuit in the CAN bus lines?













YES
There is an open circuit in the CAN bus lines.Cause

- CAN signal interruption
- Component X30/21 (Drive train CAN voltage distributor connector) is defective.
REMEDY

- Check line from control module N89 (Transmission oil additional pump control unit) to component X30/21 (Drive train CAN voltage distributor connector).
- Replace component X30/21 (Drive train CAN voltage distributor connector).
End of test







NO
There is no open circuit in the CAN bus lines.Cause

- There is an internal fault in component N89 (Transmission oil additional pump control unit).
- There is an internal fault in component M42 (Electric transmission oil pump).
REMEDY

- Replace component M42 (Electric transmission oil pump).
NOTE

- No further actions are required.
End of test







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

- Check fuse F1/6f76 (Fuse 76) in component N10/1 (Front SAM control unit with fuse and relay module) for tight installation and corrosion.
- Check lines and plug connection on components M42 (Electric transmission oil pump) and N10/1 (Front SAM control unit with fuse and relay module) for loose contacts, damages, interruptions, etc. and if necessary, repair or replace parts.
End of test