All Warning Lights on and No Speedo

[LBKRam]

Long time stalker, first time poster. I have an '03 Ram 2500 with the Hemi. It's been a phenomenal truck with 215,000 miles on it. The truck sits a lot these days and when I went to start it the other day, it started up just fine but a bunch of lights on the dash came on: Check engine, Airbag, ABS & Brake light. Also, the speedometer isn't working. I was out of town for about 3 months and I forgot to disconnect the battery this time. Battery was toast and so I replaced that and that is when the problem started. After reading through this site and a few others I checked the ground wire to the chassis (which was fine) and also did a PCM reset by pulling the fuse, and turning the key to on while waiting for the beeps. No luck. I believe the truck got some rain in it at some point as I opened the driver door one day and it was a little wet. Other posts I've read where guys had similar problems also included headlights and brake lights constantly on, wipers not working, etc. I'm not having any of those problems. The truck seems to be running just fine though honestly I haven't taken it further than 1/2 mile down the street for fear of it stalling. I have however let it idle for about a half hour and all was good. Any thoughts???