I doubt the horn has anything to do with it especially if the fuse has been removed for the horn... but you never know...

Have you checked for corrosion on the bottom of your fuse box as well? Some guys with 04's have had that problem and it caused all kinds of weird things to happen... Just a thought...

 

Does anyone know which/if control module (ECM, PCM, or other acronymn) is in this circuit? I have found that a faulty steering wheel horn switch will short to ground (through fuse 51) even when the horn fuse is pulled. I just found this and have been disconnecting the battery at night to keep from completly draining the battery. Now my gauges go out including the odometer from time to time even thought the engine will continue to run (thankfully). When the gages go out the odometer displays "no bus". I am thinking there is an instrument cluster module somewhere that this short has damaged. I would like to replace it before the engine dies.

Thanks,
OdomL