2004 GMC Sierra 1500 Z71 Drivers Side Heated Seat
 

Well I would like to start this off by saying I know wiring issues can be a pain to figure out and of course I think I might have a wiring problem. As I returned home from Christmas Vacation I jumped in the truck and started heading down the road and then I noticed that my A$$ was on fire. So I look down and sure enough the heated seat was on for the butt and back rest. Well I turn it off and said something to my wife then bam it's on again. So at this point I have decided that my seat is possessed because it just keeps running through the heat settings. Does anyone out the have any pointers on where to start troubleshooting? Thank you for your help in advance.

Re: 2004 GMC Sierra 1500 Z71 Drivers Side Heated Seat
 

It is actually a somewhat common issue. Sometimes the issue is as simple as the switch, sometimes it is the module, sometimes it is the heater element itself (though usually that issue turns it off by itself, not on as is your case).

Start off by unplugging the switch in the door. Drive around for a few days and see if the heater comes on by itself still. If so, it is likely the module under the seat. If it doesn't, reinstall the switch and see if the issue comes back, if so you may need a new switch.

Re: 2004 GMC Sierra 1500 Z71 Drivers Side Heated Seat
 

Sounds like a nice easy way to start of the troubleshooting. Thank ya.