My battery is about 6 years old and I know it is starting to get weak. I have noticed in the past month or two that after sitting for a day or more, during the first start the door locks will lock or unlock by themselves. Could this be the result of the low battery or do I have another issue?

I have ordered a new battery. I guess if the door lock problem goes away, I can take it that the low battery was the problem. I know the battery is on it way out because I checked the voltage after sitting a couple days and it was reading around 11.97 volts and it cranks slower than it used to. I know it should be at least 12.5 volts as they usually hold about 12.8 volts fully charged when new.

 

I installed a new battery and the door locks don't operate on their own occasionally now. The old battery was not that low (12.2 to 12.4 volts) when I took it out but I sure notice the difference when I engage the starter. It spins up noticeably faster with the new battery.

 

I noticed all of my Fords do the door lock/operate other items when the battery is low. Glad you got it going!

 

at work we have an 7.3 e-350 that's constantly killing it's battery trying to start (bad glow plugs) and when the battery gets low, the door locks go wild. actually locked me out yesterday haha. it's a ford thing.