Data Bus, Checking

Data Bus, Checking

Function

The engine control module communicates with all control modules capable of data bus via a CAN data bus.
Data bus-compatible control modules are connected together via two data bus wires twisted together (CAN high and CAN low) and exchange information (messages). Information not available in the data bus will be recognized as a fault by the engine control module as well as other CAN data bus control modules.
Further information: See Self study program No. 186 "The CAN data bus".

Test conditions
- A fault has been recognized by the CAN data bus On Board Diagnostic.

Special tools and equipment
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Test sequence
- Switch off ignition.
- Unlock the engine control module connector and pull it off.
- Connect test box VAG 1598/31 to engine control module. The control module wiring harness is not connected by this action.
- Check centralized matching resistor in engine control module.

- To do this, measure resistance between test box
Sockets 58 + 60
Specification: 60 to 72 Ohms

If the resistance measurement is outside the specified range:
- Replace engine control module.

If the resistance value is within the specified range:
- Repair the fault in the wiring using wiring diagram.