Theory Of Operation

The Heated Seat Switch, a momentary non-latching switch has two positions - Pressed (activating) and Not Pressed (deactivating). The Heated Seat Switch uses two Light Emitting Diodes (LEDs) to indicate the rear heated seat system status. The two system status LEDs (high/low) are controlled by the Left Rear Door Module (DMRL). Activating low, will turn on the low LED indicator in the switch, indicating the current output state is low. Activating both the high and low will turn on both the high and low LED indicators in the switch, indicating the current output state is high. Deactivating both the high and low will turn off both the high and low LED indicators in the switch, indicating the current output state is off. The color and intensity of the LEDs are controlled by the interior lighting system.

The Heated Seat Module (HSM) has three main output levels Off, Low and High. The HSM has three levels of heat output within the High setting. The HSM controls the various levels by pulse width modulation control of the output signal. When the HSM receives a CAN-IHS bus message from the DMRL, the HSM will cycle from Off to High, High to Low or and Low to Off. The first press cycles from Off to High, the next press cycles from High to Low and the next press cycles from Low to Off. The HSM has the ability to control the rear left and rear right seat outputs individually.

During an ignition cycle, when the HSM receives a DMRL bus message indicating the rear left heat switch has been pressed, the Heated Seat Module (HSM) will perform one of the following actions:

1. The HSM output will change from off to high.
2. After a maximum time of 60 minutes, the HSM will automatically change the output from high to low.
3. If the HSM receives a DMRL bus message indicating the switch has been pressed before the 60 minute time ends, the HSM will change the output from high to low.
4. After a maximum time of 45 minutes, the HSM will automatically change the output from low to off.
5. If the HSM receives a DMRL bus message indicating the switch has been pressed before the 45 minute time ends, the HSM will change the output from low to off.