AUDI A6 1995 C5 / 2.G ATW Engine Additional Signals Owner's Manual

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Rapid data transfer
HELP
Select function XX

When indicated on display
Note:
Measuring value blocks 125 and 126 indicate the participants in the
powertrain data-BUS. - Press buttons -0- and -8- to select "Read Measuring Value Block" and
press -Q- button to confirm input.
Read measurin
g value block
Q
Enter displa
y group number XXX

When indicated on display
- Press buttons -1-, -2- and -5- to select "display group number 125" and
press -Q- button to confirm input.
Read Measuring Value Block 125
1
2
3
4

When indicated on display
- Check indications in display fields 1 through 4.
CAN capable control modules connected to the Engine Control Module
(ECM) are indicated:

No indication: Control module not CAN-capable
Indication 1: CAN capable control module is connected to databus
Indication 0: CAN capable control module is not connected to
databus
Read Measuring Value Block 126
1
2
3
4

- Check under display group 126 in the same manner.
-
Press button.
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Rapid data transfer
HELP
Select function XX

When indicated on display
- Press buttons -0- and -6- to select "End output" and press -Q- button to
confirm input.
Rapid data transfer
HELP
Enter address word XX

When indicated on display
When a control module responds with its identification, the display
indicates the number of stored errors or indicates "no malfunctions
recognized".
DTCs stored in the system are indicated in sequence and printed out.
Then the VAG1551 scan tool sends the next address word. - Press button 0- twice to select "Automatic test sequence", address
word 00. Press -Q- button to confirm input.

DTC memory of all OBD capable systems in the vehicle will be
checked.
VAG - On Board Dia
gnostic
(OBD
) HELP
1- Rapid data transfer*2- Blink code output*

The automatic test sequence is over when the following indication
appears on the display
If a malfunction related to the"powertrain databus" or the "CAN-bus" is
indicated:
- Check whether the Engine Control Module (ECM) and other CAN
capable control modules installed are appropriate for this vehicle (part
no. and coding).
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If the correct control modules are installed:

- Check to be sure multi-pin connectors of control
modules are securely connected.
If multi-pin connectors are properly secured:

- Check CAN bus system

Checking a "two-line bus system"

Three or more control modules are
communicating across a "two-line bus
system".

- Analyze DTCs stored in memories of control
modules.

Note:
This analysis will help you locate the cause of the
line malfunction.
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Example 1:

From the DTCs stored in the memories, you have determined that control
module 1 is not communicating with control modules 2 and 3.
Electrical Wiring Diagrams, Troubleshooting & Component Locations Control module
DTCs stored in DTC memories:
1
Missing signal from control module 2Missing signal from control module 3
2 Missing signal from control module 1
3 Missing signal from control module 1
- Switch ignition off.
- Disconnect control modules connected across bus wires and check
bus wires for an open circuit. - Replace control module 1 if no malfunctions can be found in bus wires.
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Example 2:

From the DTCs stored in the memories, you have determined that control
module 2 is not communicating with control modules 1 and 3.
Electrical Wiring Diagrams, Troubleshooting & Component Locations Control module
DTCs stored in DTC memories:
1
Missing signal from control module 2
2 Missing signal from control module 1Missing signal from control module 3
3 Missing signal from control module 2
- Switch ignition off.
- Disconnect control modules connected across bus wires and check
bus wires for an open circuit. - Replace control module 2 if no malfunctions can be found in bus wires.
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Example 3:
Using the DTCs stored in the memories, you
have determined that none of the control
modules are sending or receiving signals.

Control
module
DTCs stored in DTC
memories:
1
Powertrain databus faulty
2 Powertrain databus faulty
3 Powertrain databus faulty

- Switch ignition off.

Electrical Wiring Diagrams, Troubleshooting & Component Locations - Disconnect control modules connected across bus wires and check
bus wires for a short circuit to B+ and Ground (GND).
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If you cannot determine a cause for the DTC
"Powertrain databus malfunction, check
whether the DTC is caused by one of the
control modules.
All control modules that use the CAN-bus are still
disconnected. Ignition is switched off.

- Connect one control module.

- Connect VAG 1551 scan tool. Switch ignition on,
and erase DTC memory of control module just
connected. End scan tool output using "End
Output" function 06.

- Switch ignition off and then on.

- Leave ignition on for 10 seconds. Read DTC
memory of control module just connected.

- If DTC "Powertrain databus malfunction" is
displayed, replace control module just
connected.

- If DTC "Powertrain databus malfunction" is not
displayed, connect next control module and
repeat procedure.
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