Reading so many posts about electrical problems in Hummer H3s I am beginning to think I have made a serious mistake buying this 2009 H3 Alpha with 112K miles on it. Replaced the radiator but that was expected. Failed to even click when turning the ign. key. Intermittent problem. Wired an auxiliary start switch. Works well. AC clutch quit engaging. Replaced the relay and now it works. This morning the engine quit several time at start-up. Just replaced air filter and wonder if that could cause this . Tire pressure light is on and won't quit. Did that a week or so ago and then went out. Tires are inflated to correct pressure.
This vehicle is unfortunately, reminding me of my Jaguar XJS. Constant problems. I am having difficulty believing GM manufactured this Hummer.

 

Welcome to HF.

If you have tech questions, please post those in the H3 section.

 

Did you clean the throttle body? They get pretty cruddy. It's best to take it off to clean it with throttle body cleaner and a old tooth brush.