Will a Loose Nut on Rear Wiper Blade Prevent Arm Movement?
 

The other day my rear wiper stopped working. I removed the 14mm nut that holds the blade arm onto the motor shaft. Before removing the nut, I realized that it was not even finger-tight. In fact it was very loose. Would this nut being loose cause the wiper to quit moving? Also, with the blade arm removed, the rear wiper control on the multi-function stalk still works. When on, the motor shaft will still turn.

The splines on the shaft of the motor appear to be completely stripped (I looked at a new motor at the parts store and it's shaft appeared to have very small (fine) splines on it). I also looked at a replacement arm sold by the parts store and it did not appear to have any splines inside the shaft hole, but looked perfectly smooth inside. This baffled me. Do I need a new rear wiper motor?

Did you try putting it all back together and tightening the nut? Could also be that without the load of the wiper the shaft does move, but it doesn't have the strength to move when the arm is on.

Thanks alwaysfords41. I will put the arm back on and secure the nut this afternoon and see if that will resolve the issue. However, seeing those stripped splines made me wonder.

Long story short: I had a fellow (less fortunate individual) detail the vehicle from head to toe and when he closed the rear glass, he pinched the wiper blade and subsequently cleaned the dash and stalks and inadvertently turned on, and left on, the rear wiper. I heard a noise after the second outing in my clean car. That's how I discovered this issue. I do not fault the man. $80 bucks for the entire job was well worth it to me. There went my savings...........

did you edit the original post about the splines or did I completely miss that part the first time around???

Sounds to me like it is stripped, but worth a try to tighten it down. Maybe there is enough spline left when it is seated all the way down. Or maybe you can get enough crush on the broken splines to still drive the motor. As a last resort if tightening doesn't work, try adding a little bit of shim stock or whatever to the interface between the motor and the arm. Even something like foil may work, just a little extra interference.

Yes, edited. Thanks and I'll give it a try.

I tightened the 14mm nut down very secure and the rear wiper is working fine for now.

Good fix!! The best kind.