Specs up front:
2005 Ford Expedition NBX

My sunroof drain got clogged and somehow water leaked down the tube and all over the fusebox (wonderful design). I only found out it was leaking down there once I started having problems and put it all together. It was very gradual. Once in a while I would get a "door sensor data error". No big deal, it would go away and things still worked. Then the auto headlights stopped working. Then the power 3rd row seats stopped, then the power locks stopped (really sucks because there is no key for the rear hatch). It would come and go. Sometimes I could go a month without an issue or somethings 5 seconds of it working then not working. I would hear a funny ticking/shuttering noise from someplace under the dash (probably by the fuse panel, but while driving it is hard to triangulate).

So I hit the forums and described the issues and started to work on the problem. I purchased a new VSM because that was the one thing everybody seemed to agree wasn't working. That turned out to not be the problem because the VSM isn't even detected by the car (old one or new one). The Ford tool could not detect it. They were able to say my old one most likely was working, just not able to talk to the car for some reason. A scary thing is that you can remove the VSM and the car starts and drives fine with the exception of the errors above (some security). I then purchased a new fusebox and all new fuses and relays because they said "the fusebox probably has a short inside it". I replaced the fuse box today and I still have the same problems. Now the suggestion is to buy new connectors because there could be corrosion on them. I have spent a small fortune with this problem. I wouldn't mind spending the money if I knew it was the solution. I feel like I've wasted good money towards nothing. New connectors are going to cost a few hundred bucks. I cant find a single one in the scrap yards or ebay. Does anybody have any experience with this issue or a suggestion of how to even track down the issue? I wish I knew all the wire outs on the fuse panel that go to the VSM so I could worry about only replacing those at least. Thanks for listening and any help would be great.

-Chris

 

This is a contradiction because if the drain is clogged, then water can't get down the tube. What you might be experiencing is the infamous windshield leak that so many have experienced. Sometimes the windshield seal wasn't done correctly at the factory which allowed water to leak down behind the dash and wreak havoc with the electronics.

The way to test for a windshield leak is to close all of the windows, start the engine, and turn the blower on high (but not the max A/C setting.) This will cause the cabin to build pressure. Now, close the doors and spray around the windshield with water. If the windshield is leaking anywhere you will see bubbles.

 

I thought the leaky windshields was only in the first gen expys?

Anyway when you lose power does the instrument panel continue to work? also, you said the auto headlights don't work but the manual headlights still do - correct? Last thing, do all of the problems always occur at the same time?

 

Can't help with the electrical, but have experience with the sunroof drains. They clogged on my 03. The water puddles and spills inside of the roof/header panels and leaks down the A pillar. When braking during/after lots of rain, water would dribble out from the grab handle and the bottom of the dash on the driver's left foot. I ran some aluminum welding wire down both sides, followed by steaming hot water and then blew them out with my compressed air gun, starting with a low pressure and then gradually increasing to a pretty high pressure. No more leaks. I think the steaming hot water followed by air gun just needs to be part of the annual maintenance, considering the expense and headache a clogged line can cause.