need some help on wiper motor wiring

[Phixius]

I am trying to install intermittent wipers on my 521.  I found a switch out of a Ford that ive modified to fit like the stock switch.  But, the ford switches positive and the datsun uses negative switching. Ive reversed the polarity at the plug and got it to work that way, but it energizes the wiper housing. and I cant change the polarity of the switch for the same reason.  the switch is metal and the housing is grounded, and its going in a metal dash... 

 

I also orderd and custom fitted my bracket for a Mazda GLC wiper motor thinking I didnt need to swap polarities. I was wrong.  Its just like the datto.

 

 

some pictures of what ive done so far

 

 

ground down old threads, and put new threads that match the datto..

 

 

Stock next to Ford switch.

 

 

 

Here is what the stock switches look like in my datto...

 

 

 

 

Ford switch installed with new threads and with the beauty ring.

 

 

 

Cut the shaft to proper length...

 

 

 

I really want to get this to work.  the delay options on it are 1 sec through 15sec

 

I feel pot committed now and dont want to scrap it.  What am I missing? How can I change the wiper motor for switched positives?

 

 

[Tristin]

Im not familiar with the Ford switch internal wiring at all, but the components Ive had to swap polarity on at work have been like this:

 

Open up the casing. There should be a diode that connects to the casing and the ground terminal. There should also be a small piece of wire connected to the positive terminal and the rest of the switch. You will want to unsolder both the diode and the wire, switch places, and then resolder them back together. Take note of the diode direction to as it only works one way. 

[thisismatt]

So the ford switch came from a vehicle that used a positive ground?  I guess I don't follow when you say the ford switches positive in the sense that, sure, it may have switched a positive lead in the ford, but why can't you switch a negative with it now (why would it have grounded to the casing if it's a positive switch, unless it came from a positive ground vehicle, which haven't been around since...???)?

[DanielC]

The 521 wiper switch is a switched ground.   This is because the 521 wiper motor uses an intermittent internal ground to park the wipers.  When the wipers are in the parked position, the internal switch is opened, but if the dash wiper switch is on (grounded) the wipers continue to run.  When you turn off the wipers with the dash switch, the internal ground keeps the wipers going until the point in the motor cycle that the internal ground is disconnected, and the wipers stop, parked.

 

If Fords are wired the same way, this should be easy.  If they are not, that the Ford intermittent wiper control applies power for a brief period of time, my suggestion is to use a relay, with the Ford intermittent switch briefly energizing the relay coil, and using the relay contacts in parallel with the Datsun switched ground switching.

[Phixius]

in the ford, the motor is grounded at all times, and the switch completes the circuit with a positive.  In the Datsun, the motor has power at all times and the swich completes the circuit with a ground.

 

 

ford switch

 

521

 

 

Tristin -- You talking about in the switch case or the wiper case?  No Diodes in either.

[DanielC]

Just for jollys, here is a 521 wiring diagram with colors.

 

The Ford diagram looks like there are three parts.  The dash wiper switch, the wiper motor, with an internal park switch, and interval governor.   I would think you need the interval governor along with the Ford wiper switch.

[Phixius]

I do have the delay box. Actually 3, two that work and one that doesnt.

 

 

So, the only way is to add a relay at each function? Run, Park, Low, and High? I cant change anything in the wiper motor itsself?

[thisismatt]

Ah, I see.  Makes sense.  The ford switch needs power to run the intermittent timer circuit on top of driving the wiper via positive side, so if I'm thinking correctly, I think you could take Dan's idea and use the ford switch to fire two relays, one for high and the other for low/intermittent.  So, the ford would energize the relays to connect to ground, essentially in place of the original datsun switch in the place of high and low.  If the governor box is accessible, I think you could modify it to work without additional relays, but you'd still need to run a separate power to it for running the timer.

 

Here is a nice large PDF of the 521 color wiring diagram: www.objext.com/521_Datsun_Truck_US Eletrical.pdf

[DanielC]

The Datsun wiper motor will run if it is grounding itself, or if it is in parked position, something else grounds the wiper motor.  I believe the blue wire on the wiper motor causes the motor to run.

I have a PDF version of a 521 service manual.  here is the page on wiper motor, and switch wiring converted to jpg.