We had a caravan do this do us. It was the body control module. About a $350 part from the dealer and it’s behind the dash and a PITA to get at. We had an independent shop do the change, and it was significantly cheaper than the dealer labor was.
140k is not too high for these vans. Our current 97 has 170k and is still going strong. We got rid of a 91 van last summer with 230k and it was still running strong…but I hit a deer with it:)