Seat Heater Mat Diagnostics

Each seat has two heating elements: one in the base (the seat heater module, comprising the seat cushion heating element and an integral heat sensor), and one in the back (backrest heating element). The seat cushion and backrest seat heater elements connect to the HVAC Control Module, although the elements are electrically wired in series (each drawing proportion of battery voltage). As well as power and ground circuits, there is a Local Interconnect Network (LIN) circuit between the seat heater module and the HVAC Control Module. The seat heater module monitors the performance of both seat cushion and backrest heaters and reports the status of the seat heating system through the LIN  connection to the HVAC Control Module. Any faults detected in the seat cushion and/or backrest heaters should trigger a DTC  to be set by the HVAC Control Module. SEAT HEATER MAT DIAGNOSTICS AND ASSOCIATED SYMPTOMS  lists the potential symptoms that may be exhibited by the seat heater system and the steps that should be taken to rectify the faults.