Advanced Diagnostics

Advanced Diagnostics - DTC U1221 (35): Motor Control Module (MCM) Lost Communication With DC-DC Converter






General Description
The motor control module (MCM) communicates with the DC-DC converter. When the MCM does not receive the signals from the DC-DC converter via the SCIDM serial line, or the received data is abnormal for a specified time, a malfunction is detected and a DTC is stored.

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






Enable Conditions






Malfunction Threshold
No signals via the SCIDM serial line are received, or the received data is abnormal for at least 2.0 seconds.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the MCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.