Checking bus system

The DTC table indicated that data exchange via the bus should be checked:

Check to be sure the multi-pin connectors of the control modules are securely connected.
Connect the VAS5051 tester or VAG1551 scan tool. See VAS 5051 VEHICLE DIAGNOSTIC, MEASURING AND INFORMATION SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .
Switch ignition on
Switch printer on via the print-button (indicator lamp in button lights up), (indicator lamp in button lights up).
Press button 1 to select "Rapid data transfer" operating mode 1.

Indicated on display

Fig 1: VAG 1551 Scan Tool Display - Data Exchange Between Control Modules, Instrument Cluster With Maintenance Interval Extension (1 Of 2)

NOTE: The address word 00 initiates the automatic test sequence, i.e. it results in a DTC check on all OBD capable systems in the vehicle via rapid data transfer.

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 sequence and printed out. Then the VAG1551 scan tool sends the next address word.

If a malfunction involving " ... databus" or " ... no communication" is indicated:

Automatic test sequence is over when the following indication appears on the display:

Fig 2: VAG 1551 Scan Tool Display - Data Exchange Between Control Modules, Instrument Cluster With Maintenance Interval Extension (2 Of 2)

Check whether the correct control module for this vehicle is installed (part number and coding).

If the correct control modules are installed, check the CAN bus system.