I have a 2010 Grand Caravan w/ just under 50,000 miles. This is a great car but for about the last 7500 miles I have been experiencing an issue where when driving on the highway around 70-75mph, the TPMS light come on and chimes, flashes for a minute or 2 and then will stay lit until I slow down for traffic or an off ramp. Ive had the van at the dealer 9 times under my manufacturer extended warranty for this issue. The diagnosis is that all 4 sensors send a 0 reading triggering the light. Chrysler replaced all 4 sensors under warranty and the first road trip it did it again, its the same diagnostic each time and the dealer simply reprograms the sensors and when I hit the road it does it again. The dealer brought up the fact I have a cell phone and an iPass (toll way pass) in my windshield that they send interference to the system. Ive owned this van since new, ive always had a cell phone and an iPass and never once had this problem. I put new Michelin Defender tires on at 29,000 miles, other than that, nothing has been changed. The sensors worked fine up until about 7500 miles. Any suggestions? Ive only got about 3 months left of my Mopar Maxcare warranty so I want this issue resolves before it starts coming out of my pocket!