This is on an 07 IC RE300 bus with the wiper switch in the left side of the dash. Its a square switch thats bolts into the dash. Part # 437281001. Ok here is the story, the original switch quit operating the washer pump but the wiper functions still worked. If you pushed it in for the washer function, the wipers would cycle a few times like it should if the washer was used. I found I wasnt getting any power out to the washer so I replaced the wiper switch and everything worked. This was the middle of Dec. The middle of Jan everything went dead, no wipers or washers. I still had the old switch so I plugged it back in and everything worked but the washer, so I got another new switch and stuck in it and everything went back to working again. About 10 days ago, while doing a pretrip, the wipers were dead again so I plug the old switch in again and back to everything but washers again so I put the 3rd new switch in and everything worked again. The next trip out the wipers worked for the pretrip and halfway through a 90 minute drive the driver turned the wipers on for about 20 minutes then shut them off. A few minutes later she went to turn them on again and nothing. I grabbed my old switch and a few tools and went over and swapped the old original switch back in again for the 4th time and it got the bus home and is still working fine today. I went back and quizzed the drivers about the switch and none of them had the wipers quit when they were being used, they were just dead when they tried to use them. This bus has doors on the front of it that you can open and swing the wiper assemblies out. I looked everything over and lubed up all the linkages on them a couple of switches ago and everything looks fine. Today I went through and used my Fluke amp meter around the wires and let the wipers run on a dry windshield for about 10 minutes, rechecking the amp load on each wire. On low each looks to pull 1.5-2 amps and 3.5 on high with the washer pump pulling 1 amp. I have never had fuse problems with the wiper/washer circuit. So is it possible I an getting a batch of defective switches or what? Pulling whats left of my hairs out on this one....
I am still running the original switch and added a push button switch to make the washers work. Wanted to see if the original will die soon. We havent had any storm since the day after I swapped the old switch back in and the wipers have always worked when the driver does a pretrip on it. I think I will leave the old switch in till school gets out and see what happens with it. (shrugs shoulders)