Here in soggy Omaha we got 4 inches of rain early monday morning and my Excursion took the brunt of it being too tall to fit in my garage. I'm thinking of naming the truck Gizmo, because you get it wet and the Gremlins start showing up...at least two of them anyways!

Gremlin #1 (we'll call him Musicus Confusicus)
I went out to the truck to leave and found the radio to be on inside...doors still locked, keys in my hand, and no one in the Excursion except Kenny Chesney (or at least his music). I opened it, hopped inside, and turned the radio off without having put the key in the ignition. I was both confused and concerned because now I thought the battery may have now been dead leaving me stranded here at home, but thankfully it wasn't. I started the truck, fiddled with the radio and all seemed to be fine...until I put it in gear to leave; that's when the audio cut out. The radio was still on but no sound, and I found that if I put the X into Neutral or Park the sound instantly came back, but only so long as you didn't try to actually DRIVE anywhere! WEIRD!!!!

Gremlin #2 (we'll call him Dooricus Irritatingus)
We all know the chime sound we get if the drivers door is opened with the key in the ignition or after having left on the headlights right? Well I now get the chiming, dinging, pinging, ****-me-off sound ALL THE TIME with the door open!!!

These electrical gremlins sure are obnoxious and I'm not certain as to where to begin figuring these issues out and solving them. I figure if any water did enter the Excursion I might be able to sweat it out, so I left the truck to sit in the sun all day with the windows opened just a sliver to let any humidity out from baking it in the heat. I lifted the floormats to check for wet carpeting and only found it to be ever so moist, and I found no standing puddles around or under the seats. After all afternoon in the sun, the air in the X was no more humid than if someone left a wet washcloth in the trunk and closed all the windows (i.e. Not very much)

Got Ideas??!! Because I'm gonna go bat-**** crazy if I don't figure this out soon.

 

Check behind the fuse block under the dash. The windshield leaks and runs down onto the PCM which makes things go haywire. I don't know from experience but that seems to be a common theme for electrical gremlins like you described.

PS: nice whitty post!

 

Did you get his autograph before he left?

 

After having just checked on the condition of the truck Gremlin #1 seems to be gone, but #2 is still alive and well. I'll pull the cover off the fuse panel and see if I can't find moisture back in there. I'm thinking off the top of my head I might be able to cut open a bread bag and secure it over the PCM to prevent water getting to it/dripping on it. Hey...that could actually work! I'm a damn genious!!!

...but not a genious enough to have gotten Kenny's autograph while he visited

 

Not sure I want to bag my ECM. I would prefer it to vent and not build up heat like any electronic item. Perhaps it might be better to just fix the leak?

 

Now, Im a country boy, but there isnt any amount of rain thats gonna get me to let Kenny get in my truck. I guess if he was gonna drown, he could sit on top.

 

Bad grounds and moister can make electrical Gremlins come alive,,!
May want to do some investigating, under the Hood and under the Ex.

 

My excursion suffers from the same #2 gremlin but i think mine is coming from the ignition because if you jiggle it woithout the key the dinging stops then comes on. maybe both your problems are in the ignition causing it to go in acc mode or something?