Glen is right - my manual says that the back & seat are in "series"
I also noticed that the MAIN components that the seats have in common are the switch & the CIRCUIT BREAKER that they use to actually drive current through the heating elements. I believe it is circuit breaker # 4 on
this page.
I will try to get the schematic, but here is the description of the circuit:
The heated seat module receives battery voltage at all times fron the PWR/HEATED SEAT circuit breaker.
When the heated seat switch is pressed, the heated seat module receives ignition voltage, through the switch, from the HVAC/DIC/DRL/HEATED SEAT fuse.
The temperature sensor inside the seat cushion heater pad senses the temperature of the cushion and signals the control unit to increase or decrease the amount of current to the seat cushion and the seat back heater elements.
Here is what should be on the pins of the Seat Heater Module connector on both sides. I am assuming this connector is under the seat:
Pin - Wire Color - Function - Comment
A - RED - Heated Seat Control - TO Seat Back element
B - Light Blue - Heated Seat Switch Signal - FROM Switch
C - Green/White - Heated Seat Switch Signal - FROM Switch
D - Yellow - Battery Positive Voltage - FROM Circuit Breaker
E - Black/Red - Heated Seat Temp Sensor Signal - FROM Seat Cushion
F - Black - Ground - TO Seat Cushion
That should be a good start for troubleshooting.
Take Care,