I recently went to start my truck after letting it sit for a few months, and found that the battery was completely drained. I went and grabbed a new battery, but after hooking it up, the following happened:

1. All of the accessories turned on (wipers, fluid, headlights, horn, etc.)
2. I can hear a whirring noise in the engine compartment, but can't pinpoint what it is.

I took the fuse for the horn out to retain my sanity, and then did the following:

1. Checked all the fuses in the box in the engine compartment. None of them appeared to be blown.
2. ​​​​​​​Unplugged the ignition switch - no effect.
3. Cleaned off the ground wires that are right near the battery and the one that's coming off the harness near the PCM - no effect.
4. Unplugged the connector from the harness to the PCM - stopped 1 and 2 from above.

I'm not quite sure what to check next, given that there seems to be a short somewhere. Any ideas would be appreciated!