SEAT Workshop Service and Repair Manuals

Function

The engine control unit communicates with other data bus-compatible control units via a CAN data bus.

Data bus-compatible control units 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 recognised as a fault by the engine control unit as well as other CAN data bus control units.

The data bus requires a matching resistor to function fault free. This central matching resistor is located in the engine control unit.

Further information:

=> Self study programme No. 186 "The CAN data bus".

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Test box V.A.G 1598/31
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test conditions

• ● The CAN data bus has recognised a fault.

Test sequence

• ‒ Remove battery.
• ‒ Release connector from control unit and pull off.
• ‒ Connect test box V.A.G 1598/31 to engine control unit. The control unit wiring harness is not connected by this action.
• ‒ Check centralized matching resistor in engine control unit.
• ‒ To do this, check resistance between test box
      Sockets 58 + 60.
      Specification: 60...72 ω

If the resistance measurement is outside the specified range:

• ‒ Replace engine control unit
  .

If the resistance value is within the specified range:

• ‒ Rectify the fault:

=> Current flow diagrams, Electrical fault finding and Fitting locations

• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-16, interrogating and erasing fault memory.
• ‒ Read-out the readiness code=> Page 01-64.