3.2.363. SPN 520395, FMI 31, ECU 1 CAN A Passive StateΒΆ

Description

An EEM4 system communication problem in the CAN A (CAN 0) bus.

Possible causes are:

  • A control unit malfunction on the CAN bus.
  • There are too many/few terminating resistors on the CAN bus.
  • The CAN bus wiring is defective.
  • A poor connection.

The CAN A bus is a powertrain bus connected to:

  • the 1.46 and the 1.47 ECU pins

Reaction in EEM

The FC is stored and the warning lamp is activated.

Solution

First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the CAN bus for a short circuit or an open load on the CAN bus.
  • Ensure that a correct software is in the ECU. Re-flash the correct software, if needed.
  • If a vehicle connector is used, check the wiring from the ECU to the vehicle connector.
  • Check the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check the ECU operation with another EEM4 controller. If the system is functional and the fault is not active with the replacement ECU, then the original ECU is defective.