Example 3:

From the codes registered by the DTC memories, you can see that none of the control modules are able to transmit or receive signals.

Fig 1: CAN-Bus DTC Memory Codes - Example 3

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• Switch off ignition.
• Disconnect the control modules which are linked by the bus wires and check for a short circuit between the bus wires
  Fig 2: Example 3 Schematic - No Control Modules Are Able To Transmit Or Receive Signals

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• Check the bus wires for short to positive and short to Ground (GND).
  Fig 3: Example 3 Schematic - Checking Bus Wires For Short To Positive And Short To Ground (GND) Circuit

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• If the cause of the malfunction "Faulty hardware" cannot be found in bus wires, check whether one of the control modules is responsible for causing the malfunction.

  At this stage all the control modules which communicate via the CAN-Bus are disconnected.

• Connect one of the control modules.
• Connect VAG 1551 scan tool or VAG 1552 scan tool. Switch on ignition and erase the DTC memory of control module which has just been connected. End Output from scan tool with function 06 "End Output".
• Switch ignition off and then on again.
• Leave the ignition switched on for 10 seconds. Then check DTC memory of the control module that has just been connected, using the scan tool.
• If the malfunction "Faulty hardware" is now indicated, replace control module which has just been connected.
• If the malfunction "Faulty hardware" is not indicated, connect next control module, and repeat above procedure.