Wiring a Common Positive Wiper Motor

PMU
1

So, there are a few topics on here already regarding wiper control, but I seem to doing it differently, so I could be wrong. Below it what I plan to do, let me know if I have it very wrong.

Using a motor from a 1992 Civic EG to upgrade the wiping on my 78 260Z. Difference being with the Honda motor, both low and high speed share a common positive and you select one of the other by switching to ground.

Will be using a Micro 5 pin changeover relay.

.

Plan is motor is powered by output 8 whenever a wiper function is requested. Wiper park signal goes to input A8

Output 07 is activated whenever high speed switch is selected and goes to the changeover relay to activate the NO pin thus grounding the high speed and removing ground from the low speed.

.

Intermittent is output via output 8, low speed but with a delay timer in the logic.

.

Would be great if I could get confirmation that this is now correct and will work as intended.

.

One difference to a normal setup is that I believe the park switch on the Honda motor is usually grounded when not parked, which would be opposite to normal. However I believe if I invert the logic it will work?

.

Is this correct logic?

OFF

If NOT parked:

Output 08 = ON

Output 7 = OFF (low speed)

When park detected:

Output 08 = OFF

.

LOW

Output 08 = ON

Output 7 = OFF

.

HIGH

Output 08 = ON

Output 7 = ON

.

INTERMITTENT

Loop:

1.Output 08 = ON

2.Output 7 = OFF (low speed)

3.Wait for park transition

4.Output 08 = OFF

5.Delay

6.Repeat

.

Also wondering if my 5 pin changeover relay needs to be protected with a diode?

Thanks for any advice. Going from doing almost no automotive wiring to wiring a full car from scratch and using a CAN network for a lot of the functions has been a real challenge but I love learning it, unfortunately I still need help for some things like this. As I have no idea if my plan is correct.

2

Anybody able to confirm? Or am I so far off that its not worth replying to someone so thick?

3

Hi,

Have you seen the Wipers module in PMU? It is available in the Project Tree. You can configure the outputs, park switch and multiple swipes patterns.

obraz
obraz595Ă—607 16.9 KB

Please remember the PMU outputs can be +12V or Hi-Z, so you can’t switch the wipers signals to ground directly.

4

Thanks. I’m happy with all that. But its more detailed towards a regular wiper setup, not a common positive one.

My only questions are regarding the setup for a motor that is always powered and switches the grounds to change from low to high speed.

As per above, the current idea is to use a 5 pin 25 amp micro changeover relay to switch the earths,

This is not from my exact setup, but the idea is the same. For mine, it will be output 8 that actives anytime a request is made for wipers (int, low, or high) For the relay it will be output 7, this will turn up when high speed is requested. For int, it will just be output 8, but with a timer programmed.

Park switch wired as normal, to input A8.

Common-positive-wiper-motor
Common-positive-wiper-motor696Ă—193 22.9 KB

5

It should work in that way if the park switch is just a switch and doesn’t need the power supply to work.

Outputs in PMU have integrated flyback diodes. I encourage you to read the pinout document as it contains a lot of useful information.

6

I believe the park switch is also ground switched, it keeps the motor grounded until its in the park position. I think that short to brake the motor happens internally in the motor and is ground side shorted.

Having trouble getting 100% confirmation on this though.

Actually, thinking about this now, I am pretty sure I don’t need to wire in the park switch to the PMU for the park function to work, I think that can go to chassis earth along with the ground wire, but I guess the PMU will need to know when it is park, so it can active the delay on timer when on intermittent setting. So it won’t provide any other function than resetting the timer.

I assumed I didn’t need the diode, but at the same time a relay with diode protection won’t hurt anything?

7

See, this is why I ask (sorry for being stupid, we can’t all be born geniuses) I think now my 5 pin relay will not work, since the motor requires constant power to apply brake.

I think instead i need to use two normally open relays. Output 8 can send constant power to the motor whenever any wiper function is requested ( I think in normal setup, this would switch with ignition signal, but with the PMU I assume that is not needed, as I could setup a timer after wiper switch is in off position, to allow power to run to the motor long enough for it to apply a brake)

The I need to use 2 other output channels, 1 to switch the low circuit relay, to ground, and one to switch the high speed circuit to ground through the other relay. I could use a 7 amp output for both of these since all they are doing is switching a relay.

8

It would be best to test the connection configurations on the bench. You would see how it works.

Park sensor should be connected to PMU, because you don’t want to leave the wipers in the middle of the windscreen after turning it off.

PMU outputs have internal diodes, external ones would do the same job, you can use it as well.

9

Thanks

Yes. Whatever I do, I will bench test it all first.v :+1:

Yes, with a normal motor setup this is true, but with the Honda motor, its all done internally, the wiper will park itself, so long as it has power until its in the park position. The park switch internally routes +12V back into the motor circuit until the wipers reach the park position. Hence why I can’t cut power to the motor for a second or two once the switch is in the off position.

I may give this setup with the 2 relays a try. But most likely my final route will now be to rewire the motor to behave like a switched positive setup and use the PMU to short it for braking with the park switch.