3.2.71. SPN 1485, FMI 31, Main relay early opening at previous afterrun

Description

The main relay has been opened without any request.

Possible causes are:

  • The battery wiring is defective.
  • The external main relay is defective.
  • The ECU’s internal main relay is defective.

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates active fault.

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 battery wiring.
  • Check the ECU connector, connections and contact surfaces (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.