Build up of debris in the wiper cowl assembly can block/slow the water drainage holes, leading to water accumulation and pooling. With 2003 model year the wiper control module (a standalone interior located module through 2002MY) functions were integrated to the wiper motor assembly itself. The water accumulation can lead to moisture ingress of the wiper motor/module and cause corrosion and shorting. Overtime this leads to erratic and often uncontrollable operation of the windshield wipers, and even cycling of the headlamps because of integrated the lamps-with-wipers function. Outlined below is a guide on cleaning the wiper cowl assembly and wiper motor control board to prevent/solve the issue. Note a severely damaged wiper motor/control may have to be replaced if cleaning the board is unsuccessful. Routine cleaning (i.e. annually) of the wiper cowl assembly is recommended on '03+ models which are stored outdoors to prevent excessive debris accumulation.
The following write-up applies to all 2003 and newer Crown Victoria, Grand Marquis, Marauder and Town Cars
==================================I found various posts about it here on CVN but not an actual writeup, so I decided to write up what I did. Hope it helps someone.
After a particularly rainy period of time, I got in the Marquis on a dry night and headed west to Cleveland. About halfway there, the wipers started coming on and off at random times. I had always heard about the Wacky Wiper syndrome but never had an issue with it before this.
I feared that it was an issue with the MFS but found upon further research that the problem is actually in the wiper assembly itself. What happens is that all sorts of nasty debris will fill up in the drain area, and when that happens...water goes up and over, into your motor!
Before I fixed it for good, I would just pull fuse 17. That will shut off the wipers, but it is not an optimal fix because it doesn't allow you to deal with the random rainstorms that might come your way.TOOLS AND SUPPLIES REQUIRED:
1. Remove both wiper arms. Lift the wiper arms up ever so slightly, pull the tabs out as far as you can, then let the wipers go. They should stay raised. At this point, the wiper arms should slide easily off.There is a small metal chuck that helps when reinstalling the wipers. They will probably fall off when you remove the wipers. You do not need these; it just helps align the wipers when reinstalling. BONUS: when you lose this chuck, you can actually reposition your wipers a little lower. I always found the passenger wiper to sit too high. No more!
2. Remove the Phillips head screws on the cowl. Some of them may be hard to see. There are five.
3. Remove all the C-clips along the cowl/wiper assembly. They should slide off easily (mine came off by hand). Set them aside.
4. Disconnect the washer fluid line at the connection nearest your driver's side hood support shock.
5. Remove the upper (plastic) cowl.
6. Remove the 8mm bolts on the lower cowl cover. There is one that has a bracket connected to the firewall on the passenger side. That one goes too.
7. Remove the two nuts on the sensor that is on the passenger side of the firewall, and pull the sensor off of the cowl. These should both be 10mm...
8. Lift the wiper assembly out of the vehicle.
9. Ungunk all of the dirt in the drain. There will be a ton. I used WD40 to loosen some of the stuck-on crap.
10. On the wiper motor itself, locate the four tabs holding the black plastic housing cover on. They will easily pry off by hand or with a screwdriver. Be careful not to break any tabs, and be careful to not scratch the circuit board inside.
11. Turn the components upside down carefully and try to get as much water out as possible.
12. Spray the circuit board itself with a light misting of WD-40. Spray the white magnet area as well with WD-40. What? You don't want to use WD-40? What do you think the "WD" stands for?
13. Using compressed air, gently spray off the circuit board and the white magnet area until dry. I dabbed my circuit board with a paper towel but I do not think this is necessary, as they both dried off very nicely with the air.
14. Around the edge of the circuit board housing, where you would expect a gasket or seal to be made, carefully smear some dielectric grease all the way around in the gasket area only. I did not put any on the circuit board itself; I do not think you should.
15. Put the housing back onto the wiper motor assembly. Do not install the assembly, but do connect the electrical connector and turn your accessories on, testing the motor for correct operation. You should be able to see definite movement, and it should work as designed. If it does not work at all, you either screwed something up or the problem wasn't wacky wipers in the first place.
16. Assuming everything from step 15 is hunky dory, proceed in reverse and put everything back together. I lost my wiper alignment chucks and therefore aligning them took about 10 minutes. However, I was able to get my wipers parked a little lower than they previously were....
I plan to do this on aknox077's car sometime soon; I will make sure when I do, I take a lot more pictures. To be honest, I wasn't even planning on doing this writeup at the time. I'm just bored at work.