Heated Seat System: Description

WARNING: This page is about a different car, the 2004 Dodge Intrepid, 2004 Chrysler Intrepid, 2004 Chrysler Concorde, and 2004 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.

Individually controlled, electrically heated front seats are available as a factory-installed option on some LH models. Vehicles with this option can be visually identified by the leather trim seats and the two separate heated seat switches mounted in the seat cushion side shields. The heated seat system allows the front seat driver and passenger to select from two different levels of electrical seat heating, or no seat heating to suit their individual comfort requirements. The heated seat system for this vehicle includes the following major components, which are described in further detail later:

Heated Seat Elements - Four heated seat elements are used per vehicle, one for each front seat back and one for each front seat cushion. The heating elements are integral to the individual front seat and seat back trim covers and cannot be removed once installed at the factory. On some models, replacement seat heating elements/sensor are available, without having to replace the entire seat cushion or trim cover. Refer to HEATED SEAT ELEMENT later in this article for additional information.
Memory Heated Seat/Mirror Module - also referred to as the MHSMM, this module contains the solid state electronic control and diagnostic logic circuitry for the heated seat and memory seat/mirror systems. One module is used per vehicle and is mounted under the drivers front seat cushion. Refer to the ELECTRONIC CONTROL MODULES for additional memory heated seat/mirror module information.
Heated Seat Sensors - Two heated seat sensors are used per vehicle, one for each front seat cushion. The sensors are integral to the individual front seat cushion heating elements and cannot be removed once installed at the factory. Refer to HEATED SEAT SENSOR later in this article for additional information.
Heated Seat Switches - Two heated seat switches are used per vehicle. One switch is mounted in each of the front seat cushion side shields. Each switch includes two Light-Emitting Diode (LED) HI/LO indicator lamps and an incandescent back lighting bulb. Refer to the DRIVER HEATED SEAT SWITCH or PASSENGER HEATED SEAT SWITCH later in this article for additional information.

WARNING: SOME VEHICLES ARE EQUIPPED WITH SEATBACK MOUNTED AIRBAGS. BEFORE ATTEMPTING TO DIAGNOSE OR SERVICE ANY SEAT OR POWER SEAT SYSTEM COMPONENT YOU MUST FIRST DISCONNECT AND ISOLATE THE BATTERY NEGATIVE CABLE. THEN WAIT TWO MINUTES FOR THE SYSTEM CAPACITOR TO DISCHARGE BEFORE FURTHER SYSTEM SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO DO SO COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

The heated seat system also relies upon resources shared with other components in the vehicle over the Programmable Communications Interface (PCI) data bus network. The PCI data bus network allows the sharing of sensor information. This helps to reduce wire harness complexity, internal controller hardware, and component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities. For diagnosis of the heated seat system or of the PCI data bus network, the use of a DRB III(R) scan tool and the proper Diagnostic Procedures are recommended.

Following are general descriptions and operations of the major components in the heated seat system. See the owner's manual in the vehicle glove box for more information on the features, use and operation of the heated seat system. Refer to SYSTEM WIRING DIAGRAMS for the location of complete heated seat system wiring diagrams.