Advanced Diagnostics

DTC U1221 (35): Battery Condition Monitor (BCM) Module Lost Communication with DC-DC Converter




General Description
The battery condition monitor (BCM) module communicates with the DC/DC converter.

When the communication information from the DC/DC converter is not received for a specified time, or when the received data is abnormal for a specified time or more, the BCM module detects a communication malfunction and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The communication information from the DC/DC converter is not received or the received data is abnormal for at least 2.0 seconds.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the PCM and MCM memory.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.