4121 - P0685 (DDE)

4121 - P0685

Information saved in
DDE

Fault code
4121 - P0685

Fault text
DDE: DDE main relay: Relay switches off too early or
undervoltage

Fault description
Error opening main relay. The system is monitored to
determine whether the main relay has been opened without a
command from the DDE (prior to termination of post-
operational shutdown phase).
If the main relay opens when it should remain closed the
counter advances by one each time the ECU boots. This
counter is stored in the EEPROM.
The diagnostic trouble code is logged when the counter total
rises above the threshold 1.

Condition for fault identification
Test condition:
This test is executed one time during initialization of the
ECU.
Voltage condition:
This test is executed one time during initialization of the
ECU.

Condition for fault memory entry
-None.

Action in service
Determine whether the error is a collateral error stemming
from undervoltage. If the error was not caused by
undervoltage:
Replace the DDE main relay.

Fault effect and breakdown warning
-

Driver information
Warning light:
MIL

Service instruction
If this error is logged together with other errors that trigger
an ECU recovery or indicate undervoltage then these
problems should be resolved. The main relay malfunction
may be a collateral malfunction.