First time I noticed this was a few months ago. After driving in a down pour, obviously using the wipers, I noticed the wipers would not turn off. They would continue to activate but sometimes stop in the top position for a few seconds and then continue to move. Turning them off or moving the wiper lever in the car made no difference. Didn't drive the car for a few days turned the car on and no issue, figured whatever circuit got wet during the rain dried.

Two days ago I had an oil cooler leak and I had to wash the under carriage. Well the wiper issue came back.

So the question is has anyone had this happen or is there anyone familiar with the wiring diagram on the 350 that could tell me where water may be getting to cause this problem?

 

You will have to troubleshoot to see if the problem is mechanical or electrical. The wiper assembly fits on a splined shaft. The splines get warn and slip inside the wiper assembly. Also look at the wiper motor. Its a collection of levers that may not be functioning properly.

Once you have eliminated a mechanical problem then it is time to look at the wiper motor electronics. Way too complicated to explain here.

 

I can almost say 100% that it's electrical. Can't see how it's mechanical when the issue returned when I washed the undercarriage.

 

Ok so finally figured out the issue. Better late than never. The issue got progressively worse in the last month so I needed to get it fixed. Turns out the IPDM had a crack on the plastic housing. Nissan wants $500+ so I tracked down a used one for less than $200. Apparently the IPDM can be the issue with several electrical gremlins so don't forget to check it when or if you have electrical issues. They are not all the same through out the model years so make sure if you need one to get one that matches your year Z.

 

IPDM is the source for many electrical issues along with the BCM, both are thorns!

Glad you got it worked out!

Also we need to catalog all the symptoms for future reference