Heated Seat System: Operation

WARNING: This page is about a different car, the 2003 Dodge Intrepid, 2003 Chrysler Intrepid, 2003 Chrysler Concorde, and 2003 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.

The heated seat system will only operate when the ignition switch is in the On position, and the surface temperature at the front seat heating element sensors are below the designed temperature set points of the system. The heated seat system will not operate in ambient temperatures greater than about 41°C (105°F). The heating elements, sensors and the heated seat switches are hard wired to the Memory Heated Seat/Mirror Module (MHSMM).

The MHSMM contains the control logic for the heated seat system. The module responds to the heated seat switch status, ignition switch status, and the seat heating element sensor inputs by controlling the output to the front seat heating elements through integral solid-state relays.

When a seat heater is turned on, the heated seat sensor located in the seat cushion heating element provides the module with an input (low-voltage) indicating the surface temperature of the seat cushion. If the surface temperature is below the temperature set point for the selected Low or High heated seat switch position, the module energizes the integral solid-state relay, which supplies battery current to the heating elements in the seat cushion and seat back. When the sensor input indicates the correct temperature set point has been achieved, the module de-energizes the solid-state relay. The module will continue to cycle the solid-state relay as needed to maintain the temperature set point. The Low heat position set point is about 36°C (97°F), and the High heat position set point is about 41°C (105°F)

The module and the heated seat elements operate on non-switched battery current supplied through the power seat circuit breaker in the junction block. The module will automatically turn off the heating elements if it detects an open or a HI/LOW short in the sensor circuit, or a open or LOW short in the heating element circuit.