Today my wife was driving the 09 Tahoe, roughly 174xxx miles, and the power steering went out and it started "chugging and hesitating" also said service power steering and service hybrid system. She also said there was a weird noise under it and I've heard that can be the auxiliary trans pump. I only see threads that end without a solution. The onboard says it's at 15 volts running and 12 with the key to just on. When I get home I can probe the battery to see what the multimeter says. Any advice or personal experience is greatly appreciated. This is a car we would be willing to put new batteries in.