I know a lot of wiper stuff has been covered at length, but I was curious about how to seamlessly integrate a Honda motor into the stock Z and wanted to understand the wiring circuit entirely. One little tidbit has been missed in a lot of this stuff.
From looking at the diagrams, what is interesting is that when the wipers are set to off, the polarity to the wiper motor is reversed. It then operates for a short time in reverse to fully park the wipers. It does this due to a little fact that the wipers will actually go lower when the motor is ran in reverse. I found this out on Zclub.net.
Heres' the quoted tidbit:
Final parking of the wiper arms. This is the clever bit which took me a while to work out. When the wipers are switched off the DC motor reverses it’s direction due to circuitry controlled by a relay strapped on to the side of the motor (this relay is used at other times too in the wiper operation). The linkage is attached to the motor via a short arm an eccentric cam bearing and coil spring. During normal operation the eccentric cam is in a position which has the effect of shortening the linkage, when the motor reverses the coil spring tightens due to the direction of travel, grips the eccentric cam, rotates it through 180’ and lengthens the linkage thus parking the wipers lower down the screen – clever eh? That’s why when switching to the off position the wiper always does a wipe – it’s to ‘park’ the wipers low down the screen.
Now the problem is that on most cars (your’s? mine was) this coil spring will be broken and so the wipers will not park fully! If you position the wiper to park low down then this will become part of it’s normal sweep and so the other end of the sweep will be short!
On the internet sites I’ve looked at nobody understands the purpose of this broken spring and because the wipers work with it broken it’s overlooked.
While I haven't inspected my spring yet, I will do so soon as well as check if it does indeed park lower. But now came the thought about whether I should upgrade to the Honda motor or not. My wipers work fine albeit a little slowly. I feel now I'd rather have a little slow working wiper, but have them park lower. I feel if I use the Honda motor, it would be guess work if the park lobes (internal contacts) are setup the same to allow the reverse park to happen.
But since I fully understand the circuit now, I figured I'd throw in a definitive answer on the best way to use the 260z or 280z with the intermittent function (as well as park, and low and high).
This diagram I found on here is correct for the hookup:
It's from a 76' 280z. Not my diagram, but kudos to BackDoorZ on here.
Here's the Wiper FSM from 74 260z:
This diagram is annoyingly hard to follow since they label the wires by function instead of color.
The 6 wires going into the motor in the diagram and their respective colors are:
B (Battery?) - Blue/Red
P (Park?) - Yellow
2 (?) - Blue/White (Yellow/Green on 77-78 280z)
E (earth) - Black
H (High) - Blue/Yellow
L (Low) - Blue - (Yellow/Blue on 77-78 280z)
As a helper I believe the S and M switch is the internal lobe contacts in the stock wiper motor. S possibly meaning "stopped" and M "moving".
The middle part of the switch shows that if the switch is in 'int'/low/high, then it sends ground down the 2 wire. This energizes a relay in the wiper motor that sets the polarity so that it's 12v on top and then gets ground for either the low or high speed windings out the bottom. Tricky part is that if you switch to the off position mid stroke, then the power to the relay is cut mid stroke, so how does it keep 12v on the top of the motor. Well, when it's mid stroke, the S/M wiper will be on M and connect ground to the P wire. But it also lets current flow throw the diode to ground (in the wiper motor) keeping that relay energized till the stroke is done. So now it's finished it's default power stroke. When it gets back to the S wiper, it will invert the power to the top of the motor (you can see the top of the motor connected directly to E (earth). If you Trace the L wire back through, you can it goes back through 3, then into the box, then out P and ultimately connects back to 12v causing the motor to turn in reverse for a given period. I take it the specific phasing and size of the low will determine how much it actually rotates back.
Here's the Honda (1997 accord, though I believe all the colors are the same):
Putting these 2 together is a little tricky, but let me explain why BackDoorZ's diagram above works. He notes in his post that the Blue/white wire is never hooked up to anything. This is because it's sole purpose is to invert the power to the stock motor.
Honda - datsun - function
Green/black - blue/red - this is constant 12v power. Basically always send power to one side of the motor.
Black - black - this is always ground
Blue - Blue - low speed wire.
blue/yellow - blue/yellow - high speed wire.
Honda's blue/white wire basically outputs 12v when the wiper is parked, and it outputs ground when it's mid stroke.
By hooking this up to the yellow wire you get the intermittent and park to work.
Looking at the 'int' diagram for the datsun, observe the 2 pole to the left of the capacitors (C1, C2). When the intermittent box actuates, it basically connects ground (E) up to M, which if you trace it back through connects to the low speed side. It probably only does this for a short moment, but enough to get the wiper into motion. But when the int box kicks off, it basically connects the low speed wire up to the P (the Yellow wire). Connecting this to the honda blue/white wire assures that you will again provide ground to the low speed wire till the wiper parks.
I know that is really wordy, but the OCD in me wanted to get all these diagrams out there for those to see why it works or to troubleshoot issues. Can help with understanding why your stock circuit is acting up as well.
ps. if you want to understand how the pie piece works on the honda diagram, assume the large part of the pie rotates and it is ground, the left small pie piece is 12v and is stationary, and the middle contact connects rides on whichever one is below it.