LI54.10-P-079533

Complaint 243: Red 12V battery message, white HV warning message, warning message in the IC and if applicable for vehicles with BMS30EB02 yellow HV drive system 465: Red 12V battery message, white HV warning message, warning message in the IC If the initial warning messages are ignored in the same ignition cycle, additional warning messages, e.g. red HV warning message and yellow HV drive system warning message may be shown. The DC/DC converter has stored a combination of the following two fault code groups: 1. P0C3B00, P0E9700, P0E5400, P0C4000. 2. P1D0B00, P1CA000, U011500. In some cases, not all DTCs from one of these groups are triggered. 243: As a consequence, on vehicles with BMS30EB02, the DTC for the auxiliary assembly fuse P0E2F00 can be set. This triggers the yellow HV drive system warning message. In the ignition cycle in which the red 12 V fault message is displayed, the DC/DC converter does not support the 12 V on-board electrical system. This means the 12 V battery may be discharged in the event of longer use. Cause In individual ignition cycles, this may result in faulty wake-up behavior of the DC/DC converter. The DCDC DTCs and warning messages may appear with a time delay. When accessing the vehicle, the white (243/465) HV warning message is displayed. When the HV system is switched on (charging, 12V supports, precon, ignition on), the yellow HV drive system warning message is displayed on the 243 with BMS30EB02 (see below for details). When the vehicle is started/PT-ready (displayed in the IC), the red 12V battery warning message is displayed for 243 and 465. Since the BMS on 243 uses the HV voltage value to check the auxiliary assembly fuse, the auxiliary assembly DTC can (with BMS30EB02) be stored as a consequence and the second (yellow) HV drive system warning message can be displayed in the IC. Remedy The faulty state of the DC/DC converter can always be rectified with an ignition change with BUS idle. The fact that the red 12 V warning message does not appear again is an indication of this. On vehicles with the yellow hybrid drive system message, it is still displayed because it is not automatically reset once the faulty state is reset. Check the DC/DC converter for functionality via Xentry Diagnostics in the workshop:
• Actuate BUCK mode for approx. 30 s
• The output current normally jumps to a high value (e.g. 100 A) and then falls slowly to the current specified value e.g. 50 A and then only changes slowly and in small increments. 243 EB311/312 (BMS30EB01): Perform reset of the DC/DC converter, e.g. through a BUS idle or by clearing the fault memory, to exit the faulty state. 243 EB330 (BMS30EB02): Clear the fault memory, since the DTC for the auxiliary assembly fuse and the yellow hybrid drive system warning message are not automatically reset. 465: Perform reset of the DC/DC converter, e.g. through a BUS idle or by clearing the fault memory, to exit the faulty state. !!! Important note: Problems in this area do not have to be invoiced on the damage code for the DC/DC converter 54720. !!! Information: Cause analysis is still ongoing in order to determine a long-term remedy. In cases in which the fault profile occurs multiple times, replacement of the DC/DC converter can be carried out. This may help delay the fault profile from reoccurring.