B272D Code - Passenger Differential Temperature Fault

The Seat Control Module E (SCME) is supplied voltage at all times, but the climate controlled seat system only operates with the engine running. The system can be operated with the ignition ON engine OFF by using a scan tool to bypass the climate controlled seat buttons on the touchscreen interface. When commanding a heat or cool mode operation in this manner, the climate controlled seat system only operates in 15 second intervals. Both voltage supply circuits are spliced together internal to the SCME, so if one circuit becomes open, both seats can still be operated. However, if a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat is disabled by the SCME.
Cabin air is drawn through and distributed to each of the blower motors located in the seat cushion and backrest. The blower motors then heat or cool the air. The air is then directed into the foam pad where it is distributed along the surface of the cushion and backrest of the seat. Once the system is activated, the SCME uses a set of flexible algorithms to control the heating/cooling modes and the blower speed dependant on the commanded climate controlled seat settings.
A differential fault occurs when the cushion and backrest blower motors on an affected seat are reporting very different temperatures to the SCME. This may result from an airflow restriction or a circuit fault of either blower motor area. If a blower motor is clear of obstruction and is operational, check the other blower motor and circuitry on the seat. It is important to note that a blower motor with a higher temperature may be operating correctly and not the area of concern. The other blower motor may be indicating a much lower temperature, causing the Diagnostic Trouble Code (DTC) to set.
If there is a temperature differential between the passenger backrest and cushion blower motor of 60 ° C (108 ° F) or more for more than 4 seconds, the blower motor is disconnected or the duct is blocked, this DTC sets. When this happens the first time in a key cycle, the SCME puts the passenger seat system into recovery mode (see principles of operation). If the system is able to recover, it functions normally. If the system is able to recover and it occurs a second time in the same key cycle, the SCME shuts down the passenger seat system.

• Restricted Passenger Cushion or Backrest Blower Motor Filter
• Faulty Passenger Cushion or Backrest Blower Motor
• Passenger Cushion or Backrest Blower Motor harness is open or shorted
• Passenger Cushion or Backrest Blower Motor circuit poor electrical connection
• Faulty Seat Control Module E (SCME)