11 years and 85,000 miles? My 25-year-old Grand Caravan has over 415,000 miles, just got home from a 1500 mile round trip, and I would stick a thousand bucks into it if I ever had to just to avoid buying anything newer with all the over-complicated, unnecessary, and unreliable computers. If you like your van half as much as I like mine, fix it.
From what you described, it sounds like one of the lock switches is sticking on. There's a number of things that can happen. One is to have a switch physically stuck, typically due to food or something getting stuck in it. A less-common cause is to have frayed wires between a door's hinges, and two are touching. Depending on the design of the circuit, a lock wire could be touching a ground wire, (or power window wire), or a 12 volt feed wire.
When you have remote keyless entry, you usually will have the driver's door on a circuit by itself because it takes two presses of the remote button to open the other three doors. That means a computer is involved, and therefore, more potential for problems. When you said a rear lock slides back to the locked position by itself, that is a major clue. A power lock motor will typically overheat when it's left energized too long and a thermal auto-resetting circuit breaker will trip. That means the locks won't be operating all the time, but when they are, they can draw enough current to kill a good battery in a few days or less.
Tuesday, September 30th, 2014 AT 10:49 PM