My daughter just bought a 69 impala 4 door sedan. The windshield wipers will not turn off unless disconnected at the wiper motor. Checked switch and fuse, everything looks good. Any other suggestions on the next step?
There is a parking switch that turns the motor off when the blades are at the bottom of the window. If the points burn up or are bent out of alignment you get to go on the wiper motor merry-go-round, as it will never cancel and turn the motor off.
did the 69 have the interior soloenoid like the 61? When I first got my 61 back in 82, we had that problem. They wouldn't engage in the AM with dew on the windshield ... then leaving school that afternoon, couldn't shut 'em off! The solenoid was sticking.
I bought the modified solid state control upgrade for my restoration.
GM original motors are cheap to buy and easy to pull. They older single speed motors w/o pulse are common in U-pull yards. To use a Multiple speed wiper motor with pulse requires a modern control stalk that makes you change out the steering column to get it (in case you are thing of going with a tilt column) and a desire to get a locking column (they don't slow down thieves for a second). This can be an attractive option compared to a used one:
Probably not helpful but here it goes. I had a buddy back in the day with a early 80s firebird, same situation, he had taken to pulling the fuse until it rained then popping it back in. Not really a solution. I took a look at it for him, for the life of me, could not trace back the problem. So always looking for a cheap inventive solution, as you do when your young and broke, I cut out the need to pull the fuse. I had a this big shiny toggle switch laying around so I mounted it in his dash and used it to kill the juice coming from the fuse. True, it didn't really address the problem, and I had to put a hole in the dash to do it. Ultimately it did the trick and 20 years later we still joke about the "James Bond" switch in his Firebird. So like I said probably doesn't help but for what it's worth its an option.
Inside the wiper motor is a cancel cam which is an electrically operated switch that pops a plastic pawl up that catches on the rotating mechanism and kills power when it rotates to the "park" position. When that plastic pawl breaks (plastic gets brittle with heat and age, and it does sit above the engine which gets hot.
It can be repaired with parts salvaged out of another working wiper motor. But then why take apart a working wiper motor to fix a broken wiper motor when the parts interchange?