Greetings, I have a 2005 Mercury Grand Marquis LS Ultimate Edition with 42k on the odometer. The vehicle is immaculate and runs perfectly with absolutely no codes... However, the wipers AND washer sprayer intermittently activate without prompt. The wipers & washers do work when commanded manually.
I recently replaced the alternator, and the battery is still showing good during tests. Battery terminals have been thoroughly cleaned and resecured. No loose or corroded grounds have been identified. I'm completely lost... Where do I go from here? I don't want to spend a small fortune changing parts till I get it right.
Thanks for all you do! Stay safe & healthy.
Possibly a defective wiper switch.
You stated the alternator was changed? did you change it? or was it changed by a tech? 1st have a scan tool diagnostic test? ( any codes) that may lead to a short circuit of that system? was the battery disconnected BEFORE the alternator was changed? check your fuse/s. strange this came about AFTER the alternator was replaced? was a earth lead not reconnected?
@normdownunder I replaced the alternator myself about 4 months ago. The battery was disconnected prior. This issue just started out of knowhere three days ago. I use a (bluedriver) scan tool & It shows zero codes. Everything is snug and all fuses appear to be in-tact.