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Hello, my name is Bobby. Thank you for the question. Can you tell me if the seat heater will ever stay on or does it do this every time you drive the vehicle?
Thank you. Sorry for the delay in getting back with me. It is possible that it is the switch but those are not a common failure. I have changed very few of them. Most of the time it is the heater element in the seat. These are the most common failure I have had that causes this. It is usually the seat bottom itself which would need to be replaced as an assembly.
The correct way to test it is with a scan tool that can see what the command is from the module when the seat is turning off. This is a dealer specific scan tool. The other way would be to test the voltage and resistance readings of the seat to see what is going on. Do you have a voltage meter?
I have attached the wiring diagram of the seats. You need to remove the connections at the driver side seat back and cushion and check the resistance. If you show and open or low resistance then you have a problem. If the values are fine then the problem is more than likely in the front SAM module.
There is not a specified resistance value. You are mainly looking for a low resistance reading indicating a short or an infinite reading indicating an open.