All of these things are controlled by the Body Computer. Computers are very unreliable and expensive, but all manufacturers have gone this route. (I believe it's one of the reasons manufacturers can't sell their cars anymore. People are sick of the frequent, expensive repair bills). You can try disconnecting the battery for a minute to see if the computer resets, but chances are it will need to be replaced.
Two warnings: First of all, the computers are tucked up behind the fuse box behind the brake pedal. Removal is quite frustrating for the professionals; it's not really a do-it-yourselfer job. In-vehicle tests can't be done on it because lowering it to get to it unplugs it from the vehicle's wiring. Whoever replaces it will want to be sure it's defective before they go through all that trouble.
The second thing to watch out for is the HVAC computer losing its mind when you disconnect the battery. '97 and '98 minivans had to be recalibrated, but I don't think that was a problem with '99 models. The calibration procedure can be very frustrating, and will not complete if the AC isn't working properly.
The most common problem with these body computers is total failure of the wipers. Usually the washers still work. I've seen at least one person install a switch on the dash to run the wipers on "high", but that's not the proper repair.
Friday, June 19th, 2009 AT 10:27 PM