Audi A8 1994 Service Manual page 74

Audi A8 1994 ➤
Electrical system Self-diagnosis 02.99 ➤ - Edition 05.2002
- Check data bus system.
Testing "two-wire bus system"
- Assess faults stored in control units.
Note:
Assessment helps to localise wiring fault.
Example 1:
Faults entered in fault memories reveal that control unit 1 has no link with control units 2 and 3.
Control unit Faults entered in fault memory
1 - No message from control unit 2
- No message from control unit 3
2 - No message from control unit 1
3 - No message from control unit 1
- Switch off ignition.
- Disconnect control units linked by bus wires and examine bus wires for open circuit.
=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
- Replace control unit 1 if no faults are found in bus wires.
Example 2:
Faults entered in fault memories reveal that control unit 2 has no link with control units 1 and 3.
Control unit Faults entered in fault memory
1 - No message from control unit 2
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01 - Self-diagnosis
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