I looked under my hood today and noticed my Coolant Fan Delay Relay was disconnected. The connector seems to be a little corraded, but what exactly does this piece do? I hooked it back up and haven't noticed anything different. It was the closest connnector to the engine, not the back one.
The large relay is the fan delay. It turns the fan on for a few minutes if the temperature hits a certain level after the engine is switched off.
They have a habit of sticking and running the battery down at times with age.