windshield wipers behaving badly

[exboatracer]

I've got a wierd problem with my wiper motor. Wipers work but they dont turn off when I shut them off, eventually they will turn off but usually in the wrong spot(like in the middle of the windshield!) Once in a while they will actually stop in the correct position.My swap is a 2003 5.3 into a 1990 xcsb.Thanks for any help on this.

[someotherguy]

Bad wiper behavior on a GMT400 truck is 99.9999% ground issues. Either some grounds got missed or disrupted during the engine harness modification, or the circuit board inside your wiper motor is suffering as many of them do. It seems less common on the 1988-1990 motors but 1991-up are notorious for it. The 1991-up are dead easy to fix if you're handy with a soldering iron and takes practically no time at all. 1988-1990 are slightly tougher due to more work to fish the board out of the motor, but still an easy job.

Once you've looked over your engine compartment grounds and are sure nothing's missing or damaged, turn your attention to the motor. The socket on the circuit board where the harness plugs in is the problem area. The harness weight pulls against the socket and over all these years eventually cracks the solder joints. Sounds crazy but any EE will tell you solder is a great electrical connection but a poor mechanical one. Once you look at the board you'll see the first pin at the edge of the board is the ground (trace runs all the way around the board where grounds are tapped to the different paths.) Intermittent/bad connection here is the source of practically all the wiper motor issues. Resolder all 5 joints for the socket-to-board and you're good to go.

Richard

[exboatracer]

Thanks for the quick reply Richard, I will check that out for sure. I'm not too sharp with electrical problems but really confused on this one because wipers worked great before the swap! I was wondering if I took too many wires out of my original harness,or left something out when reconnecting the wiper motor. At any rate thanks a bunch,and glad to see you on this site.

[someotherguy]

Yeah, if they worked great before the swap then I'd say the likely suspect is a ground that got damaged or removed. It's also possible the harness just got yanked one time too many and finally put a flaky joint on the board over the edge. Usually I would immediately suspect the joints but the history of working fine/then engine swap = problems, makes it more of a 50/50 either way.

Grounds have a funny way of finding their path through wherever they can. When the proper ground is missing, sometimes other paths will do, with unpredictable results.

Richard

[exboatracer]

Richard,let me throw this out there---- would a missing resistor have anything to do with my problem? (someone mentioned that to me).Just thought I'd ask. Thanks.

[someotherguy]

Missing resistor? Not sure where they are thinking that would be. The whole laundry list of wiper issues are pretty common and always come down to ground issues. Won't park in the right spot, won't turn on, won't turn off, missing the intermittent speeds, sprayer won't work even though pump tests out, etc.

Richard

[exboatracer]

Alrighty then,I'm all over the grounds and if need be, into the motor and board! Thanks.

[exboatracer]

Richard, you were spot on, it was a bad ground, thanks for your detailed info!

[someotherguy]

No sweat...wish everything was that easy, like figuring out the harness nightmare pretending to operate the LS1 in my Suburban!

Richard

[exboatracer]

I wish I could help you out with your problem,but I'm bad when it comes to electrics, thats why I went with a stand alone setup, and then just pieced things together from there. My only problem now is my idle dosent bump up when my a/c is turned on which makes the belt flop around. By the way that suburban of yours looks great,and I'm sure you'll figure it out. It's always easier to do it from scratch yourself then try to redo someone elses work!