Scania CMS DTC 520 CAN communication

CMS CMS control unit · Scania

Code 520 (decimal). Some diagnostic tools show it in hexadecimal as 0208.

In short

Communication error or overload on the orange CAN bus.

Applies to: CMS1 (CMS)

What does Scania CMS fault code 520 mean?

Communication error or overload on the orange CAN bus.

What causes Scania DTC 520?

The fault may be due to: - Fault in the control unit connections to the orange CAN bus (pin B29 or B32). - Fault in the cable harness or connections to the orange CAN bus. - Short circuit between voltage supply and wake-up signal (control unit pin B38).

What are the symptoms?

Functions dependent on the orange CAN bus may be impaired, e.g.: - Automatic vehicle level control. - Differential lock. - Fuel consumption calculation.

How to fix Scania CMS fault code 520?

  1. Check the connection of the orange CAN bus to the CMS control unit (B29 and B32).
  2. Measure the resistance between the CMS control unit pin for the orange CAN bus CAN High (B29) and CAN Low (B32) with the battery disconnected.
  3. Resistance should be around 60 ohms.
  4. (Due to the two termination resistors connected in parallel.)
  5. Measure the resistance between the CMS control unit CAN High (B29) and CAN High on other units connected on the orange CAN bus with the battery disconnected.
  6. Resistance should be close to 0 ohm.
  7. Measure the resistance between the CMS control unit CAN Low (B32) and CAN Low on other units connected on the orange CAN bus with the battery disconnected.
  8. Resistance should be close to 0 ohm.
  9. Check the CMS control unit wake-up signal (15) on pin B38.

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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