why won't my heated seats stay on in my 2005 sierra truck?

You turn them on and they turn right back off.

Yes. They go off in about 5-10 seconds

While you are sitting in them and when they are turned all the way up? There should be some sort of safety inside where the heater will shut off when no one is in the seat and also when it hits a certain temp. If your SRS or air bag light is on then I would have to guess the pressure sensor in the seat is bad. If no lights then I would have to guess its the thermal safety switch.

Hello 66man, I'm sorry to hear that you're having this issue with your Sierra. I would suggest reviewing your truck's Owner's Manual pgs. 1-5 & 1-6 to that discusses the heated seats and how they work. If the heated seats still don't function properly, I would suggest taking your truck into your GMC dealership to be serviced. Vanessa GM Customer Service

John, My 2005 is doing the same thing, with no SRS or warning lights on. I found the wiring diagram but before I start chasing wires and tearing apart my truck.. where is the thermal safety switch located? Also, I couldn't find one online to purchase if I do need to replace it, any suggestions on where to find one?