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2002 Ford F150 wont start after it rains

We purchased a used 2002 Ford F150 about four years ago, and in the past couple years, we’ve noticed that it won’t start after it has sat out in the rain. It goes completely dead, no response, nada. We’re usually in the clear since we have a garage, but the garage also doubles as my husband’s carpentry shop, so sometimes the vehicles sit outside when projects are in process. We are concerned about being able to travel with this vehicle due to its unreliable nature regarding weather…

An internet search showed other are having the same problem, and one person thought it had to do with the windshield leaking moisture onto electrical circuit boards. We’ve taken it in for a look, and the mechanics couldn’t come up with any explanation. Any ideas? Have you heard of this before?? Thanks.

What is the battery’s voltage? Could it be a starter relay? Can you test to see if voltage is getting to the starter?

Not sure what the battery’s voltage is. I do know it’s an Autocraft Titanium battery. The starter works fine other than after/during a rain.

I just walked outside to find the truck attempting to start by itself, with no keys in the ingnition, so we unhooked the battery for now. It was trying to turn over, and the parking lights were flashing. It’s strange that it really is only after it’s been raining, even though we can’t find any leaky spots.

I would check the switch and relays (including the solenoid) I would also want to see a voltage reading with the engine running, at idle; and while trying to start.

I am inclined to agree with the previous advice. I think that the problem is with a bad starter “relay”. Does your truck have the solenoid mounted directly on the starter? If it does then the relay is mounted on the fender and looks similar to the old Ford solenoid. When this relay fails it can cause a no start or self start in wet conditions. See if your starter relay is damp.

I’d love to say I understand you guys, but…I’m a girl who didn’t learn anything more than how to change the oil and rotate/change tires. We’re going to a friend’s tonight, and he might know more about this. I’ll print out your replies, and let you know how it goes. Thanks!!

I have recently started to have the same electrical problems. Today, Sept 29,2010, I pulled the entire dash out and all the seals from around the winshield looking for the leak. What I found was that the windshield had a very small leak in the top drivers side corner. i found it by chance when it started to rain heavely. The water ran down the A-pillar and down on the fuse panel and GEM. I also found that there is potential for water to enter the cab through a bad seal job above the top door hinge on the driver’s side. If I was you I would remove the seals for the exterior and have someone spray it while you are inside looking for a leak or any drips. Hope this helped

Yes, if the GEM or FEM gets wet, it will drain the battery after several hours.