Alright I could not find any posts covering this so I decided to make one. I have an 02 Caravan 3.3 and all the accessories went wacky when it would rain. The wipers, windows, heat, radio, and windows would not work. I would only happen while driving in the rain. Imagine that the wipers stop working in the rain. I have seen a couple people with this problem but not a very in depth solution. I am not sure why you would take off the fuse box cap and then throw it away, but that is what the previous owners did to my caravan, so there was a lot of corrosion. Anyways I decided to tear apart the pdc and share the process.

Start by talking out the battery and then push the tab on the right side of the fusebox to the right and then tilt it up. You will have all the connectors under here. Disconnect all of them by pulling down on the red tabs first then pressing the center tabs and pulling the connector out. Be easy on these because if you break the plastic on the fusebox it will not be repairable. Once you have all the connectors off then you need to take off the connectors holding the fusebox legs in. They are grey and should be easy to take off. The fusebox will only come out at an angle as you can see by the shape of the legs.

Now comes the fun part. Set up a little table that will not be disturbed for the duration of this repair so that none of the little parts get lost. After you get everything set up start by taking off the FCM on the front. You will need a T-15 Torx bit. Then take out all the fuses and relays and putting them on your table exactly the way you took them out of the fusebox like this
http://www.use.com/media/2012/1221/3016333/p_005.jpg
For beginners I would recommend taking pictures of everything before you start removing anything. After you have all the fuses laid out pull the four tabs on the sides and pull off the top cover and you should now have something that looks like this.
http://www.use.com/media/2012/1221/3016333/p_011.jpg
Now you have to pull off everyone of this little clips. To do this quickly get a paper clip and make a little hook on the end of it. On the back of these clips there is a little hole you can grab with the hook. Get a small screwdriver to fit in the clip and tilt it to the side then pull up on the paper clip and it should come off.
Once they are all off take off this plastic piece then we are ready to take it out of the bottom plastic frame. Turn the unit over to view the bottom. Make sure all of these pins are free to come out or you will break one trying to get it out. One of my pins was so corroded that even after cleaning it off it broke trying to get it out. It was no problem soldering back in but you dont want it to happen if you can help it. Once all the pins are free it should gently slide out of the plastic frame, you might have to help it a little, just make sure it comes out straight or you will bend and break a lot of pins.
Now that you are down to the guts of the unit look for any burnt traces like this
http://www.use.com/media/2012/1221/3016333/p_006.jpg
Over time the heat will wear on these traces that are used most often and you will notice that the epoxy has come off in this area as well. If they look like this they might be bad, but you need to do a continuity test to find out. Once this green enamel has come off from the circuit board it will be eroded by moisture until it breaks.
To do a continuity test put one end of your circuit tester on the pin that the trace comes from and follow the trace to the other pin. If the light comes on it is good but you might be getting some resistance. If the light does not come on then you need to solder a wire from one point to the other.
After that clean up all the contacts that have corrosion on them. It will be worse in some states than others because of the salt. Here is a picture of some of my contacts eaten away by corrosion. I could not see the contact at all before I cleaned it.
http://www.use.com/media/2012/1221/3016333/p_007.jpg
Once everything is all cleaned up put it all back together carefully.

For the original problem that I took this apart for was the accessories going wacky and that was a problem at the connector. It was eaten in half and completely disconnected from the fusebox. Here is the pin that was missing and needed to be soldered back together to get my accessories back online.
http://www.use.com/media/2012/1221/3016333/p_012.jpg

 

Lots of great info and presented very well. I'll be moving this to my files. No doubt I'll be using this to help others in the future. Thanks for taking the time to put all of this together. By any chance do you recall the culprit wire/contact? The color of the wire? Was it the power feed to the accessory relay or something along those lines?

 

Well I cant be certain that this was the only culprit as there was so much corrosion on all of my contacts that it could have been a combination of pins. The thing with these caravans is it is hard to tell since the FCM handles most accessories and if it does not receive power or receives less power than it should I am guessing that it will not function properly. I am betting that this was the case for me because going down the highway, in the rain, The radio would come on by itself and then shut off. Then the wipers would go out. The blower motor was intermittent and I was pulling my hair out. This is the reason I decided to do the overhaul.
Next time I am under the hood I will take my multimeter and pin down the culprit and also the color of that wire.