Weird seat heater problem
 

Hello, I have searched for the fix. Hopefully I can find answers here. When I'm driving alone and turn my heater on it works fine, I can reach over and turn the empty passenger side on as well. It also works great. When I have a passenger ride in that seat, both seat heaters will not work. They will turn on for a sec then off. But when someone is sitting just right on the passenger side the heaters will work. . . until they move wrong, then they turn off. Rear seats work great. I'm not sure is there is a pressure switch that senses weight on the seat or its either the butt or back heater or neither. That side was under a little bit of water awhile ago. Winter is right around the corner and I'd like to fix the problem. Any ideas would be greatly appreciated. Thank You. 2005 Hummer H2 and believe it or not just under 400,000 miles!!! Still runs great

most likely the heater element inside the seat is going bad. shorting under the circumstances you described.

Welcome to HF. All vehicle questions go in the section for your vehicle..... ie. H2 questions all go in the H2 section. Si I moved this for you.

The attached wring diagram and description may help you diagnose.

Can't find any reference to a pressure switch, that's not to say there isn't one.

There could be some over/under current monitoring and it looks like there are thermistors that monitor the temperature.

So water ingress could be fooling the temperature sensing or may be passenger weight is shorting or disconnecting something?

Keep us posted

Thank You

Thanx oceanbrave.

So today at work during lunch, after I started the H2 I hit the seat heater back button so the whole gig turns on. Works great. Then I told the passenger to jump in and turn his seat on. They both worked great, heated up quickly. Then I asked him to jump around in the seat to see if it would turn of. He couldn't get it to turn off for nothing. Rocking back and forth bouncing around on the seat. He also "tested" it on the way back from lunch as well. Both seats worked great. So I will be doing this off and on for awhile to see if I can get it to do what it did last year and turn off. Last year it was instant, soon as the passenger sat down, bang, it would turn off. So I guess "if it isn't broke, I'm not gonna fix it". But this was really weird. I just want my GF to have a warm seat this winter when we go places in the Hummer.

I had this EXACT same problem. I replaced the heating elements under the leather seat cushions and they have worked ever since. You definitely have a heating element problem.