2008 F350 horn activates all by itself whenever truck gets wet. This can be during washing or even driving in the rain.

rust on the pin switches on your door frame remove and clean them.

I'm having a problem with my right headlight on my crown 2008 crown vic, whenever it rains my right headlight won't turn off, even when there's no key in the ignition, sometimes it turns on by itself if the car is out in the rain, any help would be much appreciated

Did the problem come on suddenly or was some previous action or work done......

Sun roof drains are clogged

If you have a wet seat then it is likely defective weather stripping around the window.

Try this. If the floor is dry, then it rains and the floor remains dry, only gets wet after a drive in the rain or on wet streets, you may have a hole somewhere.

Check for holes from missing rubber grommets or holes in the floorboard or firewall from rust. Check for any rust holes or missing rubber grommets under the car or on the firewall, anywhere water can splash up into the vehicle from driving in rain or running through puddles..

Check wet spots along the carpeting all the way up under the dash, if the wet spot is higher than the floor itself, you could be getting the water from splashing through puddles.

Any holes under the car or in the fenderwell even up on the firewall can cause this problem.

First check for any obvious signs of rust, if none are found then look for missing or defective rubber grommets.

You have a leaking windshield seal at the bottom of the windsheild rain gutter.

check on the passanger side of the car to see if the floor is getting wet as well because it sounds as if your computer is getting wet behind the glove box while at home on a nice day wash the car and check it all over for leaks because the computer or something is getting wet in the car it may be a bad seal around the windshield

The spare tire well is pooling water, check there. GM knows about it, but won't say it's a factory defect. Sorry, I'm in the same boat you are. See here: http://ww2.justanswer.com/uploads/Bluegorilla/2008-10-09_134337_08-08-057-001a.pdf

Sounds like you need new wires and or cap and rotor, had the same problem on my jetta 1.8L when I would drive it in heavy rain it would bog down and misfire. The water blows threw the rad right onto your distributor and wires causing the short (old and cracked or just defective). Try it out I'm sure that will fix it.