Electric door lock problems

[TheApocalyptican]

Sometimes my door locks open and close as they should. For some reason I notice that they seem to work better after driving and stopping and then using them. Almost like after the truck is driven, the door locks work once or twice like they should, and until I take the truck for a drive again, they won't always pop open, and will barely pop closed. I found the relay for the locks, but messing with it and the connections to it makes no difference. I was thinking maybe a ground problem? But where would I look for the wire?