My Mustang GT 2002 has a problem with whipers. rolling switch whipesrs doesn work. I have replaced the multifuntion swith with a brand new but still not working. I had checked fuse's relayy, wiring and connectors and they are good. someone told me that coulbe malfunction in Smart Juntion Box. someone could help me how can solve this situations because y dont use the car because rain time in Mexico city

 

Welcome to the forums!

I sent you a PM regarding where you can find a good shop manual for your car to download. Reason being I'm not thrilled with the where, but it's clean if you click the *correct* big blue button. Other reason: Well... reasons. Let's leave it lay. I'd fully understand if you do not trust that link, or me, and don't go to it or download it at all, and that'd be fine. Point will be that you need the wiring for that entire setup to understand what's next.

Page 3866 of that PDF is Section 501-16. This discusses the wiper/washer system and diagnostics involved to figure out what's wrong.
Go ahead and read it, but you'll just really wind up starting at page 3872 of the manual to do the pinpoint testing. Unless you have that fancy code reader, then go for it, let it tell you what's wrong and proceed.

You'll wind up at "The wipers are inoperative" and that'll send you to Pinpoint Test B
That's on page 3874 and on. Follow that and you'll have the problem figured out and taken care of soon enough.

Gotta love diagnosing electronics.

Oh, and by the way, on page 4210 is the Wiper/Washer circuit from switch to motors and other boxes involved, in case it helps you on how it all sorta works, electrically speaking.

I do hope that helps, and sorry for the weird PM thing. I just really didn't want to put that here. I'm probably too paranoid about it, but... well, there we are. Good luck!