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Three or more control units communicating via a "two-wire bus system” > < Checking a "two-wire bus system”

A3 Mk1

Two control units communicating via a “two-wire bus system”
   
Two control units communicating via a “two-wire bus system”
–  Switch off ignition.
–  Detach the multi-pin connectors at both control units.
–  Check whether there is an open circuit in one of the bus wires → Current flow diagrams, Electrical fault finding and Fitting locations.
  A01-0024
–  Check whether there is a short circuit between the bus wires → Current flow diagrams, Electrical fault finding and Fitting locations.
  A01-0025
–  Check whether there is a short to positive or short to earth in one of the bus wires.
If no fault is detected in the bus wires:
  Note
A defective voltage supply may also be the cause of an impaired CAN bus communication.
–  Check voltage supply for both control units.
  A01-0026

Three or more control units communicating via a "two-wire bus system” > < Checking a "two-wire bus system”