Test module, data transfer

This test module should be implemented when data transfer to several control units is faulty.

Preconditions

Diagnosis cable and tester

Before carrying out this test module, make sure that the diagnosis cable and tester are in working order. If necessary, carry out diagnostic procedure on another vehicle or check the diagnosis cable with the self-test function.

The "diagnosis cable self-test" (in administration) checks whether the diagnosis cable and the diagnostic interface in the tester are in working order. For this purpose, the diagnosis cable must be connected to the test socket at the rear of the tester.

Test procedure

Testing data transfer

Data transfer is checked between three control units connected to the diagnostic bus or K-bus.

• Test of communication with control units on the diagnostic bus (TxD link).
  The following control units are addressed: Engine control unit, ABS/ASC, instrument cluster
  
• Test of communication with control units on the K-bus.
  The following control units are addressed: ZKE general module, electronic immobiliser (EWS), light switching centre
  

Whether the data bus is generally defective is determined on the basis of the determined fault symptoms (communication with one or several control units faulty).

Instrument cluster

The instrument cluster internally connects the diagnostic bus with the K-bus (gateway). The data telegrams are converted by the tester and sent via the K-bus. If data transfer to the instrument cluster is faulty, consequently, data transfer to the control unit connected to the K-bus can also not take place.