First off, I know this post is extremely long and I do apologize. I just thought that the more information, back story, etc. the better. I tried to add any information that I thought may in some way actually be relevant to the issue I'm having.

I have a '96 Ford Windstar. Over the coarse of a few months last year, I noticed that no matter how careful I was getting into the van on rainy days, the carpet on the drivers side was always wet. I should note that I live in Washington state which as you all know, is an extremely wet state. One day my dome light started to behave strangely. The next day I noticed that my turn signals had a slight delay. One day later my turn signals stopped working all together. After hitting Google for a couple hours, I came to the conclusion that I had the dreaded leaky windshield issue. Subsequently, over time water had managed to get down into the fuse box soaking a few of the relays which in turn caused the electrical issues. As a cheap fix I used flow-able silicone around the perimeter of the windshield in an attempt to stop the leak. I also pulled all fuses and relays from the fuse box. I opened each relay and sure enough a few contained moisture, some were corroded, and some completely fried. I soaked the fuse box in CLR, thoroughly rinsed it with fresh water, and allowed it to completely dry before reinstalling new fuses and “good” relays I pulled from the local junk yard.

The work I had done last year seemed to fix the problem. No more electrical problems, and no more wet carpet. Then a few weeks ago, the rainy weather started to hit hard again. I did notice that although not soaked like before, the carpet on the drivers side did seem to have a very small area that always seemed to be slightly wet. I assumed that this time it actually was from just getting in and out of the car and I'm still thinking that this MAY be the cause although not 100% sure yet.

Last week I went out to the Windstar late at night to get something that I'd left on the passenger seat. I noticed that the light on the rear glass defogger button was lit. I pushed the button to turn it off thinking it was stuck. The light stayed on. No, the key was not in the ignition. Being late and not wanting a dead battery in the morning, I disconnected the battery for the night.

The next morning I reconnect the battery and head out to run a quick errand. While driving, I noticed not surprisingly that the light on the rear glass defogger button was still lit. At this time I started to wonder if the windshield had actually started leaking again and that the relay controlling the rear defogger had gotten moisture in it.

Now for the scary part:
When I arrived at my destination a few minutes later, I had the idea to just pull that particular relay as a temporary fix until I had time to work on the van that weekend. One at a time, I put a finger on each relay and pushed the rear glass defogger button until I found the correct relay. I popped the hood and disconnected the negative battery cable. I went back into the car and pulled the relay I had thought to be defective. I then loosely reconnected the negative battery cable. When I looked up, I saw smoke coming out of the open driver's door. I quickly disconnected the negative battery cable again. When I returned to the inside of the van I noticed the smoke was coming out from behind the dash on the driver's side, somewhere in the area of the fuse box.

Panicked and not knowing what to do next, I randomly pulled about five more of the relays. While doing this, I also noticed that I had inadvertently left the key in the ignition so I pulled the key out before returning to under the hood. Next, I reconnected the negative battery cable. To my horror, not only was even more smoke spewing out of the open driver's door, but also a very loud noise which kind of sounded similar to a windshield washer fluid pump motor but louder, seemed to be coming from the back end of the van. At the time the only thing i could think of was that it must have been the fuel pump being blasted by too much current or something. I quickly disconnected both terminals from the battery, waited an hour, then had the van towed back to the house.

The next day I removed the trim and panel that hides the fuse box area so I can assess the damage. After spending over an hour looking around with a flashlight and mirror I was shocked to find that I could find NO burnt wires or even a clue as to anything that may have gotten hot. I even pulled off some of the protective covering of the wiring harness that feeds into the top of the fuse box and found nothing suspicious. I then removed all remaining relays from the fuse box the opened each one looking for obvious damage or moisture. No moisture was found in any of the relays. And only one relay had what appeared to have corroded contacts and a very small area of the white internal plastic which had turned brown from getting hot. This spot was about the size of a pin head. If this would have been enough to fill the van with smoke, I don't know but am curious if anyone could tell me.

Now I know that what I did next was most likely not safe, smart, correct procedure, etc, but desperation sometimes causes desperate actions.. Without the key in the ignition, I took one relay and plugged it into the fuse box, I then touched the negative battery cable to the terminal of the battery, after not hearing the same noise from the back of the van I then loosely connected the negative battery cable to the terminal, I then quickly ran to the drivers side with a flashlight to see if I could find anything starting to smoke in hopes of getting an idea of what may have been shorting out. I saw no smoke. I waited about a minute and still no smoke. I disconnected the negative terminal from the battery, reinstalled one more relay, and repeated the process.

After installing about the sixth relay, as soon as I touched the negative battery cable to the negative terminal I could once again hear that sound coming from the back of the van. I immediately pulled the battery cable away from the battery. The relay that had been installed last was labeled “Door Unlock”. I removed that relay and placed it in a different socket. I repeated my previous process and after a few more relays I heard the noise yet again. This time the relay was labeled “Door Lock”. I removed this relay and repeated the process until all remaining relays were installed including the blinker relay (all other relays are identical).

With all relays except “Door Unlock” and “Door Lock” installed, I reconnected the battery and spent about ten minutes looking and smelling for smoke. I noticed nothing. I then attempted to start the van and it did start and run.

Assuming now that the sound I had been hearing coming from the back of the van was the rear hatch lock actuator, I removed the trim from the hatch, disconnected the actuator, reinstalled either the “Door Unlock” or “Door Lock” relay (I don't remember which), reconnected the battery, and YES no loud noise this time! I then pulled the lock relay back out and disconnected the battery one last time and that is how I left it.

Now the big question... What do I do now? To be honest, I really can't afford to take this to a mechanic. Could that relay I found that was so slightly burned actually be what caused the van to fill with smoke? If not, other than leaving the rear hatch lock actuator plugged in, reinstalling one of the lock relays, and actually waiting 30 seconds or so for something to smoke, is there some other test I can do to see if something is actually shorting out? Aside from just leaving the two door lock relays uninstalled, at this point I honestly don't know what to try next. What would be the most probable? A short, bad switch, bad actuator, ....? I do have the wiring diagram for the electronic lock system if that helps but after looking at it for a couple hours, I'm not sure where the problem would most likely be. Keep in mind, that actuator makes noise as soon as the battery is connected with no key in the ignition and only if either one or both door lock actuators in installed.

 

Without even looking at the diagram,
What happens if you disconnect the plug to the rear hatch and plug in the relays?
If you get any kind of spark when reconnecting the battery cable you have just eliminated the latch assy.
Now you need to open the driver's door panel and examine the door lock switch assy and disconnect that , then install the relays and reconnect the battery cable, now what do you get ? You just eliminated the wiring and driver's switch.
That might be one way to eliminate different sections one at a time until you can isolate the area/component that is apparently shorting the circuit.
Your logic seems good , but you ran into a roadblock and hopefully these suggestions might provide an alternate path to choose.