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Injection system: repairs > < Components and functions

Leon Mk1

Data bus: checking
   
Data bus: checking
Special tools and workshop equipment required
t  Manual multimeter -VAG 1526B-
t  Measuring tool set -VAG 1594C-
t  Tester -VAG 1598/31-
t  Current flow diagram

Basic
Communication between the engine control unit and all the control units prepared for data bus is produced through a CAN data bus.
The control units capable of data bus are connected together via two data bus wires twisted together (CAN_High and CAN_Low) and exchange information (messages). Faulty information on the data bus is detected by the engine control unit 1 and by the other CAN data bus control units and registered as a fault.
Test requirements
l  If a self-diagnosis of the CAN data bus has detected a fault: → Vehicle diagnosis, testing and information system VAS 5051
Test sequence
–  Switch off ignition.
–  Release connector from control unit and pull off.
   
–  Connect tester -VAG 1598/31- to control unit cable harness, without connecting engine control unit cable harness.
–  Check the central terminal resistance incorporated in the engine control unit:
  E01-0168
Tester -VAG 1598/31-, socketTester -VAG 1598/31-, socket
5860
Specification: 60 ... 72 Ω

If the resistance measurement is outside the specified range:
–  Replace engine control unit: → Vehicle diagnosis, testing and information system VAS 5051.
If the resistance value is within the specified range:
–  Eliminate the fault from the wiring using the current flow diagrams: → Current flow diagrams, Electrical fault finding and Fitting locations.
   

Injection system: repairs > < Components and functions