Scania MBS DTC 543 #Not implemented. Absence of CAN bus 3 communication

MBS MBS control unit · Scania

Code 543 (decimal). Some diagnostic tools show it in hexadecimal as 021F.

In short

The fault is validated as present if the ECU does not detect communication on CAN bus 3 within the timeout period

Applies to: MBS3 (MBS)

What does Scania MBS fault code 543 mean?

The fault is validated as present if the ECU does not detect communication on CAN bus 3 within the timeout period

What causes Scania DTC 543?

• Defect wiring for CAN bus 3. • Defect ECU unit(s) on CAN bus 3.

How does the system react?

Functions dependent on information from CAN bus 3 are degraded/missing in MBS (Master)

What are the symptoms?

MBS expansion node J, K, L and M are connected to CAN bus 3, meaning that components connected to those nodes may not work as intended.

How to fix Scania MBS fault code 543?

  1. Trouble shoot CAN bus 3 cable harness and connectors.
  2. Check connector for CAN bus 3 on MBS
  3. Check wiring for CAN bus 3:
  4. Measure the resistance (with the battery disconnected) between CAN-high and CAN-low.
  5. It should be close to 60 ohm (one 120 ohm termination resistor in each end of the CAN-bus).
  6. Measure the resistance (with the battery disconnected) between CAN-high on MBSM and CAN-high on any other unit on CAN bus 3.
  7. It should be close to zero ohm.
  8. Measure the resistance (with the battery disconnected) between CAN-low on MBS and CAN-low on any other unit on CAN-bus 3.
  9. It should be close to zero ohm.

This information is for guidance only. Always follow the manufacturer workshop manual and safety procedures; if in doubt, contact an authorised workshop.

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