I recently had a problem with my door locks, too. For awhile the driver side lock was a little problematic. Sometimes when I would try to lock both doors with the switch the driver side lock would make some noise but not fully lock. Then one day I could not get the locks to do anything with the switch (both with the truck running and with it turned off). I figured it was the fuse but the fuse was fine. That week the weather turned cold at night and my battery gave up the ghost. It turns out the battery was nine years old (a Kirkland battery from Costco).

I installed a new battery and lo and behold my power locks work perfectly every time.

 

you probably have a little prong in the driver's switch that isn't making full contact. the newer battery has more juice and is overcoming the small gap more effectively. If you pull the switch and bend the prongs to make good contact, it should have started working just fine again and end up being slightly cheaper than a new battery.

But at nine years, it could be due

 

It was definitely due. It wouldn't even start with a jump. It sputtered but that was it. I was impressed that it lasted as long as it did.