New "Mad Max" subscriber, bought a 72 240z about a month ago. Last night at midnight, leaving a bar in the rain, turned on the wipers. The arms moved about 30 degrees and stopped. The wipers have been working at both low & high speeds until now, but now nothing happens. No fuses are blown. I'm mechanically & electrically competent. Please tell me how to troubleshoot this problem like is it the motor, the linkage, the switch, electrical, etc. It's been raining a lot here in San Jose, CA. Thanks for reading!

I would start with eliminating the wiper motor, disconnect it and apply power to it and see if it works. Alternatively hook a multi meter up to the disconnected wiring harness and see what voltage is reading at the terminals when you turn the wiper switch on. Check your Haynes manual for polarity color coding on the wires.

Chris

Test if there's voltage of about 12v on the motor. You probebly need some new brushes in your motor... a possibility..... after 47 years? ?

It could also be the 2 main spindles that the wiper arms attach to, there is no means of lubricating them without removing the wiper arms, the cowl panel, disconnecting the linkage at the motor to see how stiff the movement is.   Since you have to go that far to test the motor anyway you can test both at the same time,  but then after 47 yrs you should probably pull both out for some maintenance.

Many members have found that those spindles caked with dust and rust are the real cause of slow or seized wipers. 

Thanks everyone for the suggestions! It's supposed to stop raining soon, so can go outside and give these tips a try. 

Here's what I've found: when the wiper is turned on, if I "help" the wiper arms then it cycles normally. After raising the wiper arms, the motor can turn the main spindles, but really noisy and slow. Shot the main spindles and linkage joints with cleaner followed by lube. Now the wiper function is working again and quieter, but only when the windshield is wet. Maybe still need to pull the linkage and main spindles out again for a serious cleaning. Shouldn't be very difficult.

Dismayed by how sluggish the wiper operation is, at either speed. Maybe it's working good as new and maybe it's near total failure. Might be time to look at a wiper motor upgrade with harness.

Thanks to everyone who replied!

 The wipers were barely adequate when they came from the factory, and they get worse at speed. 80 mph and above they start to lift.

Something similar here happened to my Z, I reccomend that you do the honda wiper motor conversion, it pretty much bolts right up and requires very little modification. Just go to your nearest pick a part and I think its the wiper motor out of like a 2002 civic or accord. Just google search 240z honda wiper motor and there are a few great write ups. 

While you’re at it, disassemble your wiper linkage a grease up the whole thing and replace the c clip holding on the main linkage thing.