4.2.194. SPN 520204, FMI 4, ECU Main Relay 2 short circuit to GROUNDΒΆ

Description

The high and low power outputs of the ECU are supplied via the main relays (the FET transistors). When short circuit to ground or battery is detected, Main relays (MR) will automatically shut off. To ensure whether the short circuit to GND or bat is either temporary or permanent, the MR shall be reactivated after the delay time. If the monitoring system detects a continuous short circuit to ground or bat, the MR will be shut off.

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:

  • Measure the Pin (K46) from wiring terminal, to see if there is a short circuit to ground.

Solution2:

  • Check the ECU operation with another EEM4 controller. If the system is functional with the replacement ECU, then the original ECU is defective.