i replaced my mfs about 3 weeks ago because my last on was acting up. when i did the harness was in bad shape so i bought the 2 differnet repair harnesses and repaired the(soldered) connections and the harness is good as new. For some reason the wipers on the new switch are not working right. When i turn the on nothing happens until i get to high and then they come on, when i goto turn them off they don't turn off. The only way i get them to turn off is to turn the engine off and start the truck again. Sometimes they start wiping when i start the truck and i have to turn it off then on 2 or 3 times to get them to stay off. i took the switch back and got a replacment but it acts the same. My washer fuild continues to pump so i had to unplug the motor. If i hook up my old switch it actually works better than the new one as far as the wipers go but my dimer switch doesn't work. Does anybody know if these switches vary some from year to year and they gave me the wrong one? It is a 99 f150 I just can't figure out why both switches do different things if it is a wiring problem i would think they would act the same. If anybody have any suggestions i would love to hear them because this is driving me crazy!!!!!!!! thanks

 

Put the truck's year in your profile so it's easier to find.

 

thanks for the advice, that ought to fix it.

Luckily i did figure it out. My truck is a 99 and i bought the switch from o'reilly auto. after it didn't work i thought maybe it was defective so i took it back and exchanged it for a new one. that didn't fix it either. That led me to belive that the problem was in the wiring so i tore into all that and repaired it thoroughly. That still didn't fix it so i drove it around and put up with the crap for about 2 weeks. I called the ford dealer today and priced a switch $160-twice what the first one cost me. I asked him what years that switch showed to fit, he said that it would fit 99 to 04. I then called o'reillys and asked them for a switch for a 98 and what do you know, same # as they gave me for the 99. So i went to ford and had the guy look up both the 98 and the 99 switch, they are identical visually but different part #'s. I bought the one they had and took it home and installed it. What do you know it works. Long story short. although some of these switches look the same they are very different internally, and o'reillys doesn't have this figured out. It should be a nice discussion tomorrow when i go back to see them. Maybe this will help someone so they don't go through all the crap i did.