Part 1

No CAN message was received from control unit A80 (Intelligent servo module for DIRECT SELECT).


Possible cause:

- Check the CAN communication with control unit A80 (Intelligent servo module for DIRECT SELECT).
- Engine compartment CAN databus
Affected functions:

- Power generation

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Test 1: CAN communication is faulty.

Test 2: Engine compartment CAN test

1. CAN communication is faulty.

Test 1.1: Check the CAN communication with control unit A80 (Intelligent servo module for DIRECT SELECT).

1.1. Check the CAN communication with control unit A80 (Intelligent servo module for DIRECT SELECT).

Test 1.1.1: Check the CAN communication with control unit.

1.1.1. Check the CAN communication with control unit.
Warning!Communication with ECU required.


2. Engine compartment CAN test

Test 2.1: Procedure in case of CAN faults

Test 2.2: Read current CAN configuration and CAN fault codes

Test 2.3: Further CAN test options

2.1. Procedure in case of CAN faults

Test 2.1.1: How do I quickly reach my goal?

Test 2.1.2: General test information

Test 2.1.3: General CAN fundamentals

Test 2.1.4: Possible aids and their usage

2.1.1. How do I quickly reach my goal?
How do I quickly reach my goal?First call up menu item 'Evaluation of CAN fault codes' in case of CAN timeout fault codes and communication errors.The resulting tests must be performed.Menu item 'Further CAN test options' should only be called up if the above-specified tests do not produce the desired result.Note:Menu item 'General test information' can be called up for an explanation of the different CAN fault types.

2.1.2. General test information
Notes on CAN fault codes:CAN timeout fault

- A CAN timeout fault code is set due to the absence of a CAN input signal.The cause of this may be not only the transmitter control unit, but also the CAN networking.
- For example:No CAN message was received from control unit A.
Bus OFF fault

- A Bus OFF fault code is set, when the control unit cannot send a certain amount of messages to the CAN bus or the messages are incomplete.The control unit then switches off for a short time from CAN bus.
- For example:CAN controller: CAN bus OFF
Functional CAN fault

- A functional CAN fault code is set because of an implausible CAN input signal.The cause of this is not the CAN networking, but the transmitter control unit or its sensors.
- For example:CAN signal 'A' from control unit B is implausible.
Notes on CAN faults that cannot be read out as fault codes.Bus wake-up event

- An event that wakes up the bus without reason is designated a bus wake-up event.
- The cause of this is not the CAN networking, but the transmitter control unit or its sensors.
- Further possible causes of fault:
- Magnetic fields caused by nearby high-voltage installations, railroad installations or power plants.
- Magnetic fields can radiate on to lines and control units in rare cases and cause undefined behavior in the control units.
- The special tool 'Star Diagnosis CANtool' can be used to log bus wake-up events, bus keepawake events and other signals.
Bus keepawake event

- When a control unit keeps communication on the bus awake without reason, this is designated a bus keepawake event.
- The cause of this is not the CAN networking, but the transmitter control unit or its sensors.
- Further possible causes of fault:
- Magnetic fields caused by nearby high-voltage installations, railroad installations or power plants.
- Magnetic fields can radiate on to lines and control units in rare cases and cause undefined behavior in the control units.
- The special tool 'Star Diagnosis CANtool' can be used to log bus wake-up events, bus keepawake events and other signals.


2.1.2. No further information available.


2.1.3. General CAN fundamentals

Test 2.1.3.1: Low-Speed CAN (83,3 kBit/s)

Test 2.1.3.2: High-Speed CAN (125 kBit/s , 500 kBit/s)

2.1.3.1. Low-Speed CAN (83,3 kBit/s)
General CAN fundamentals
Low-Speed CAN (83,3 kBit/s)

- 83,3 kBit/s : For example:Interior CAN bus Series 211

- This CAN bus enables single-wire mode.
- 'Single-wire mode' means that fault-free communication between the control units is still possible even if one of the two CAN lines fails.
- This CAN bus does not require external terminating resistors.
Legend and description for figure 1CAN-H: CAN bus High CAN-L: CAN bus Low ECU 1 ... n: Control unit 1 ... n Legend and description for figure 2U 1: Specification approx. 3,6 volts U 2: Specification approx. 0 volts U 3: Specification approx. 2,5 volts U 4: Specification approx. 1,4 volts U 5: Specification approx. 5 volts Continue with button F2













2.1.3.1. No further information available.


2.1.3.2. High-Speed CAN (125 kBit/s , 500 kBit/s)
General CAN fundamentals
High-Speed CAN (125 kBit/s , 500 kBit/s)

- 125 kBit/s : Interior CAN bus Series 221
- 125 kBit/s : Telematic CAN bus Series 221
- 500 kBit/s : For example:Drive train CAN bus
- 500 kBit/s : For example:Diagnostic CAN-Bus

- This CAN bus does not permit single-wire mode.
- This means that both CAN lines are always required for fault-free communication between the control units.
- This CAN bus requires external terminating resistors.
- The terminating resistors can be located in control units or voltage distributors depending on the CAN bus.
Legend and description for figure 1CAN-H: CAN bus High CAN-L: CAN bus Low ECU 1 ... n: Control unit 1 ... n CAN terminating resistor ( Example: 120ohms )Legend and description for figure 2U 1: Specification approx. 3,6 volts U 2: Specification approx. 2,5 volts U 3: Specification approx. 1,4 volts Continue with button F2













2.1.3.2. No further information available.


2.1.4. Possible aids and their usage
Evaluation of CAN fault codes

- The control units present in the vehicle (actual configuration) are compared with the coding in control unit CGW (specified configuration).
- Filtering and evaluation of all CAN timeout fault codes present in the vehicle. The result of the evaluation leads to the required test steps.
Multimeter

- Aids for voltage and resistance measurement in menu item 'Measurements with multimeter on CAN network'
Measuring system

- Aid for graphic representation of CAN signal and voltage levels
- The specified characteristics shown in Measurement Technology are used to recognize changed CAN voltage levels, which can be caused by faulty CAN components.
- Possible procedure: Disconnect and then reconnect the CAN bus subscribers at the voltage distributor one at a time.Compare the pass image with the actual image from the oscilloscope.
Star Diagnosis CANtool

- Aids for representation of actual values and identification of bus wake-up events and bus keepawake events
Continue with button F2

2.1.4. No further information available.


2.2. Read current CAN configuration and CAN fault codes
Warning!Communication with ECU required.


2.3. Further CAN test options

Test 2.3.1: Information to engine compartment CAN network

Test 2.3.2: Measurements with multimeter on CAN network

Test 2.3.3: Test with the aid of the measuring system

2.3.1. Information to engine compartment CAN network

Test 2.3.1.1: Arrangement diagram. NOTE: Some of the control units listed are special equipment and not installed in every vehicle.

Test 2.3.1.2: Wiring diagram of CAN bus

2.3.1.1. Arrangement diagram. NOTE: Some of the control units listed are special equipment and not installed in every vehicle.
Location diagram (with special equipment)
Figure legend

- A1 (Instrument cluster)
- A76 (Left front reversible emergency tensioning retractor)
- A76/1 (Right front reversible emergency tensioning retractor)
- A80 (Intelligent servo module for DIRECT SELECT)
- A89 (DTR controller unit)
- N2/7 (Restraint systems control unit)
- N3/9 (CDI control unit)
- N3/10 (ME-SFI [ME] control unit)
- N15/7 (Transfer case control module)
- N15/9 (Rear axle differential lock control unit)
- N47-5 (ESP, SPS [PML] and BAS control unit)
- N51 (AIRmatic with ADS control module)
- N71 (Headlamp range adjustment control module)
- N73 (EIS [EZS] control unit)
- N80 (Steering column module)
- N93 (Central gateway control unit)
- X11/4 (Diagnosis test connector)
- X30/19 (Voltage distributor connector (CAN C), front passenger)
- Y3/8n4 (Fully integrated transmission control (VGS) control unit)
- Installation point of plug connection X30/19 (Voltage distributor connector (CAN C), front passenger)
- Communication with ECU required







2.3.1.2. Wiring diagram of CAN bus
Note

- WIS is not available on this system.
- It is not possible to display the requested WIS document [ pe0019p2200maa ].
- You can start WIS on another system and display the WIS document by entering the document number [ pe0019p2200maa ] in the 'Contents' field.


2.3.1.2. No further information available.


2.3.2. Measurements with multimeter on CAN network

Test 2.3.2.1: Voltage supply of engine compartment CAN control modules

Test 2.3.2.2: Resistance test of engine compartment CAN

Test 2.3.2.3: Test procedure ground cable

2.3.2.1. Voltage supply of engine compartment CAN control modules

Test 2.3.2.1.1: Check power supply at control unit A1 (Instrument cluster).

Test 2.3.2.1.2: Check power supply at control unit A76 (Left front reversible emergency tensioning retractor).

Test 2.3.2.1.3: Check power supply at control unit A76/1 (Right front reversible emergency tensioning retractor).

Test 2.3.2.1.4: Check power supply at control unit A80 (Intelligent servo module for DIRECT SELECT).

Test 2.3.2.1.5: Check power supply at control unit A89 (DTR controller unit).

Test 2.3.2.1.6: Check power supply at control unit N15/7 (Transfer case control module).

Test 2.3.2.1.7: Check power supply at control unit N15/9 (Rear axle differential lock control unit).

Test 2.3.2.1.8: Check power supply at control unit N47-5 (ESP control unit).

Test 2.3.2.1.9: Check power supply at control unit N51 (AIRmatic with ADS control module).

Test 2.3.2.1.10: Check power supply at control unit N71 (HRA [LWR] control unit).

Test 2.3.2.1.11: Check power supply at control unit N73 (EIS [EZS] control unit).

Test 2.3.2.1.12: Check power supply at control unit N80 (Steering column module).

Test 2.3.2.1.13: Check power supply at control unit Y3/8n4 (Fully integrated transmission control (VGS) control unit).

Test 2.3.2.1.14: Check power supply at control unit N2/7 (Restraint systems control unit).

Test 2.3.2.1.15: Check power supply at control unit N3/9 (CDI control unit).

2.3.2.1.1. Check power supply at control unit A1 (Instrument cluster).
Note:If the fault code is not current, it may be deleted. In this case, the battery voltage was too low over an extended period.Charge the battery, if necessary.Question:Is the fault current in several control modules?Note:This fault could result in consequential faults. You should therefore process this fault first and then erase the fault memory.

YES
Possible cause and remedy

- Battery voltage too low.Test battery.Charge battery, replace if necessary.
- If fault occurs again:Check alternator.Communication with ECU required
- The quiescent current is too high.


NO
Test voltage supply Terminal 30.
Note

- Switch picture with function key F7
Test prerequisites

- Battery voltage is OK.
- Fuse F3f11A is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component A1 (Instrument cluster).
- Measure direct voltage with multimeter between sockets (A1) 1 and (A1) 4
Specified value

- Voltage [11.0...14.5] V
Question: Is the measurement value OK?













YES
The measurement value is OK.Possible cause and remedy

- Perform inspection of connector and of socket for bent pins and enlarged contacts.
End of test

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

- Check lines from control module F3 (Cockpit fuse box) to component A1 (Instrument cluster) against wiring diagram.
- Line from component A1 (Instrument cluster) to component W29/2 (Ground (right A pillar))
End of test







2.3.2.1.2. Check power supply at control unit A76 (Left front reversible emergency tensioning retractor).
If the fault code is not current, it may be deleted. In this case, the battery voltage was too low over an extended period.Charge the battery, if necessary.Note:This fault could result in consequential faults. You should therefore process this fault first and then erase the fault memory.Question:Is the fault current in several control modules?

YES
Possible cause and remedy

- Battery voltage too low.Test battery.Charge battery, replace if necessary.
- The quiescent current is too high.Test quiescent current.
- If fault occurs again:Check alternator.
Do you want to continue with function 'Alternator test'?

YES
Note on alternator test; Depending on the engine variant, different alternators are installed.

- Alternators without networking
- Alternators networked with engine control unit
Networked alternators can be diagnosed via the engine control unit.Detailed information on alternator testing can be found in WIS.Press button F2 to go to WIS documents

2.3.2.1.2. No further information available.


NO

2.3.2.1.2. No further information available.


NO
Test sequence

- Switch off ignition.
- Disconnect coupling 1 at component A76 (Left front reversible emergency tensioning retractor).
- Measurement at connector 1
- Measure direct voltage with multimeter between sockets (A76) 1.5 and (A76) 1.4
- Measure direct voltage with multimeter between sockets (A76) 1.5 and (A76) 1.6
Specified value

- Voltage[11.0 ... 14.5] V
Question

- Is the measurement value OK?


YES
The measurement value is OK.This test did not produce any clear result.Possible cause and remedy

- Inspect connector 1 at control unit A76 (Left front reversible emergency tensioning retractor) for damage, correct connection, loose contact and corrosion and repair, if necessary.
- A76 (Left front reversible emergency tensioning retractor)
End of test

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

- Line between component A76 (Left front reversible emergency tensioning retractor) and component F4f29 (Fuse 29)
- Line between component A76 (Left front reversible emergency tensioning retractor) and component W17/1 (Ground, left rear seat)
End of test

2.3.2.1.3. Check power supply at control unit A76/1 (Right front reversible emergency tensioning retractor).
If the fault code is not current, it may be deleted. In this case, the battery voltage was too low over an extended period.Charge the battery, if necessary.Note:This fault could result in consequential faults. You should therefore process this fault first and then erase the fault memory.Question:Is the fault current in several control modules?

YES
Possible cause and remedy

- Battery voltage too low.Test battery.Charge battery, replace if necessary.
- The quiescent current is too high.Test quiescent current.
- If fault occurs again:Check alternator.
Do you want to continue with function 'Alternator test'?

YES
Note on alternator test; Depending on the engine variant, different alternators are installed.

- Alternators without networking
- Alternators networked with engine control unit
Networked alternators can be diagnosed via the engine control unit.Detailed information on alternator testing can be found in WIS.Press button F2 to go to WIS documents

2.3.2.1.3. No further information available.


NO

2.3.2.1.3. No further information available.


NO
Test sequence

- Switch off ignition.
- Disconnect coupling 1 at component A76/1 (Right front reversible emergency tensioning retractor).
- Measurement at connector 1
- Measure direct voltage with multimeter between sockets (A76/1) 1.5 and (A76/1) 1.4
- Measure direct voltage with multimeter between sockets (A76/1) 1.5 and (A76/1) 1.6
Specified value

- Voltage[11.0 ... 14.5] V
Question

- Is the measurement value OK?


YES
The measurement value is OK.This test did not produce any clear result.Possible cause and remedy

- Inspect connector 1 at control unit A76/1 (Right front reversible emergency tensioning retractor) for damage, correct connection, loose contact and corrosion and repair, if necessary.
- A76/1 (Right front reversible emergency tensioning retractor)
End of test

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

- Line between component A76/1 (Right front reversible emergency tensioning retractor) and component F4f24 (Fuse 24)
- Line between component A76/1 (Right front reversible emergency tensioning retractor) and component W17 (Ground, right rear seat)
End of test

2.3.2.1.4. Check power supply at control unit A80 (Intelligent servo module for DIRECT SELECT).
Operation number of operation texts and work units or standard texts and flat rates:27-0641Test sequence

- Switch off ignition.
- Disconnect connector at component N15/5 (Electronic selector lever module control unit).
- Switch on ignition.
- Measure direct voltage with multimeter between 5 and 4
Specified value

- Voltage[7.0...16.0] V
Question

- Is the measurement value OK?







YES
The measurement value is OK.Possible cause and remedy

- Replace component A80 (Intelligent servo module for DIRECT SELECT).
Additional measures

- Perform initial startup.
- Continue with button "F2"







Initial startup
The following procedure will guide you through all steps required to perform a complete initial startup of system ISM.Preconditions

- The new control unit must have already been installed.
You will be guided through the following steps

- Detach transport protection.
- Perform calibration.
- Personalizing
- Activating
Start process with button F2.

Warning!Communication with ECU required.


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

- Check fuse f111 (voltage supply from control unit ISM) in component F58 (Engine compartment fuse and relay box).
- Check all affected plugs, connectors and electrical components for damage, loose contact, corrosion etc. and repair if necessary.
End of test







2.3.2.1.5. Check power supply at control unit A89 (DTR controller unit).
Check power supply at control unit A89 (DTR controller unit).
Figure legend

- A89 (DTR controller unit)
Test prerequisite

- The voltage test at component G1 (Battery) is o.k.
- Fuse 117 in component F58 (Engine compartment fuse and relay box) is o.k.
Test sequence

- Switch off ignition.
- Detach coupling at component A89 (DTR controller unit).
- 1.Measure direct voltage with multimeter between sockets 1 and 1.6
- Switch on ignition.
Specified value

- [11.0 ... 14.5] V
Question

- Is the value o.k.?







YES
Note

- 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
The measured value is not within the specified value range.Possible cause and remedy

- Cables between component F58 (Engine compartment fuse and relay box) and control module A89 (DTR controller unit)
- Plug connection MR4
End of test