A4 Quattro Wagon V6-2.8L (AHA) (1998)
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Check bus wires for short circuit to B+ or Ground (GND).
If there are no malfunctions in the bus wires:
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As a test, replace one of the control modules. Select a control module that will take the least amount of time to replace and cost the least amount of
money.
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If communication between the control modules across the bus is still interrupted, replace the second control module.
Three or more control modules are communicating across a "two-line bus system"
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Analyze DTCs stored in the memories of the control modules.
Example 1:
From the DTCs stored in the memories, determined that control module 1 is not communicating with control modules 2 and 3.
Control module
DTCs stored in DTC memories:
1
- Missing signal from control module 2
- Missing signal from control module 3
2
- Missing signal from control module 1
3
- Missing signal from control module 1
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Switch ignition off.
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Disconnect the control modules connected across the bus wires and check bus wires for open circuit.
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Replace control module 1 if bus wires are OK.
Example 2: