My daughters 97 F150 just started having Keyless Entry issues yesterday. The panic horn just started going off for no reason. Just replaced the car battery last week. The only thing different is it has been raining like crazy the last couple of days. Also, her key fob does not work, and hasn't since we got the truck. I didn't know this until this morning. I will be replacing the fob battery when she gets out of school today. Any ideas on the possible cause? Also, is there a way to disconnect/ deactivate this until I can get the problem resolved?

 

I suspect a windshield leak that is allowing water to get into the control module under your dash.
Open that up and look for moisture/corrosion.

 

Yep sounds like a leaking windshield and a wet GEM

 

Ok, so rain has been gone for a few days and haven't noticed the panic alarm issues. Couple of things noticed, passenger side looks like it been broken into at some point, key lock cylinder is so screwed up that you can't get the key into it. Tried to replace the jamb switch in that door, but can't find the correct replacement. If the truck was broken into at some point, could this problem be from changing out the ignition switch? I'm just trying to get a couple of different causes just in case. And where is the GEM located?
Another issue that has been going on since we purchased the truck is intermittent no start. Turn the key to "run" and everything is normal. Try to start it, nothing. No clicking like a dead battery, nothing. Checked all the battery connections and everything is clean and tight. New battery. Replaced starter solenoid. Not sure where to check from here. It's driving me nuts because, she has taken over my F350 in the mean time.

 

IIRC correctly the GEM is located under the dash on the passenger side. Getting water inside from a leaking windshield causes corrosion and shorts which result in the kind of behaviors you are describing.

 

Not quite. 97-03 is on the driver's side of the bottom half of the dashboard. It is the 'backpack' to the Fuse box (AKA Junction Box) It's slightly annoying to remove and wiggle free, but not too difficult. Easiest method I know of is to pull the GEM and fuse box together.

I had mine out a couple months ago as I wanted disassemble the fuse box to re-route the fog light circuit. Didn't have much luck getting it open after 20 minutes, but it was just a side project while waiting for a new dimmer switch to arrive. But on the plus side, I did find out who Ford for them from. It will be useful for when I add a couple circuits later.

The door jamb switch (AKA door ajar switch) is part of the latch assembly. If it is sticking, keeping the interior lights on, try spraying some PB Blaster in it, then open/close it 10x. That's how I freed mine up.
The only link between the door lock cylinders and the ignition switch is that they share the same physical key dimensions, nothing more.

If it is falling on its face with the key in START, I would look at the Starter Relay on the firewall. Find the Mega Fuse block, then go toward the passenger side about 2", following the cables.

Chances are the Starter Relay is not getting a good, clean ground from the sheetmetal, indicating you have an issue between the cab and battery. I'd wager both of the Cab-Chassis ground straps are failing. Certainly wouldn't be the first time, my passenger side one completely disintegrated as I was removing it to be replaced with a proper weather-capable 4awg cable when I redid all of the truck's grounds.

The only other bit of advice I have is that if you're going to go to the trouble of redoing one vital link in the ground plane, do the rest as well. Properly soldered 4awg cables will outlive crimped ones, and will be far more reliable and resistant to corrosion than the chintzy straps Ford used. Seriously, exposed braided copper being constantly subject to moisture, salt and other nasties being flung up from the passenger side front tire is NOT how you make something reliable...

Make no mistake, redoing the battery/starter/ground cables is a a pretty intrinsic job. Not necessarily complicated, just a bit of a PITA to extract the old ones. Plus, it means getting some Marine Battery Terminals too. I absolutely swear by these because they work miracles.

$5 for the terminals and the time/effort to solder your own cables is well spent for reliability. Including the Stainless Steel bolts I've grown fond of use for electrical connections, redoing the power/ground and starter cables cost me $30 and took about 3-4 days total. But afterwards, it starts up effortlessly every time and every circuit I rehabbed works better than the day it came out of the factory.

I did things a little different than Ford did though, by re-routing a couple things to eliminate redundant parallel connections and tied everything together on a dedicated ground bus bar.

 

I'd look at the electrical connectors behind the kick panels on both sides. mine were corroded and causing power lock problems.
I had to bypass one of the connectors as it was so badly corroded there was no saving it.