Mike Simard

I need to wire a wiper motor for my racer using a common toggle switch.
There are 6 wires:
1-ground
3-motor, are there 3 speeds?
2-park circuit

The motor unit seems similar to other Bosch units with the exception of the 3rd motor wire.

My questions are:
Do I use 2 of the 3 motor windings independant of each other for low and high?

Can the park circuit have ign 12v+ on one side and the other side tie into the low speed motor winding or would the park circuit need to be wired to only pass current in the switch "off" position?

Lizard928

53a and 31b go to the intermitant wiper relay which performs the park function.

The others are power from int wiper relay, lo, and hi.

Do you have the ability to use the combo switch on your steering column still? Or is that gone?
For my track car this is one part I am leaving on it so that I can easily control the wipers without thinking.
When racing you want to have to think about less items on the car. Leaving it factory will make it so that you can do it instinctively without having to remove any concentration from actually driving.

Mike Simard

31b does go to the intermitant relay and eventually to the low speed brush. Park and Int' are both done at the low speed.
If 31b were wired straight to the low speed brush(53b), that would take care of parking anytime 53a was hot which would ideally be when the wiper switch was in the off position, wired to ign power.

A simple wiring should be a SPST switch supplying 53b and ign power on 53a thus giving you a single (low speed). That would be simple but what if you want to use a DP switch and have a high speed by supplying 53 or 53i in it's second position? Well, my big question about that is whether it's OK to have the low speed 53b hot while the high speed is used? Would supplying more than one speed be bad? Inneficient? No big deal?

If that's no big deal than that's the only way a toggle would work for 2 speeds.

The other option would be to use a seperate relay and have 53a get power when the wipers are switched off. So much for simplicity.
There's no way I'm using the original stalk.
It's a dilema!

Mike Simard

Well, I just did some bench testing and answered my question.
You cannot supply more than one speed at a time.

Lizard928

Why not use a higher amp 2 way switch and put power in to it, and then out to lo/hi. That way center is off, one way is low, the other is high?

I dont think supplying power to both high and low will hurt it. but the last thing you want is to loose wipers and not be able to drive because of it.

You might also just get a VW rabbit rear wiper motor and just do a single wiper blade instead. The wiring for those is much simpler

Mike Simard

The reason you can't use a 2 position switch for hi-lo is because the parking. You would have to have the parking circuit hot with the wipers off and common toggles switches can't do that, you'd have to add a relay to the mix.
If you could keep the low speed energised when running in hi, that would allow simple wiring for the park circuit by using a 2 way toggle and ign power to the park but as I found out the wiper motor will revert to the low speed with both speeds hot. That's too bad.

Wiring for one speed with a SPST toggle is still very simple and it parks. Anything more gets complicated but doable with a relay and DPDT switch.

Alan

The park switch is not designed to handle high current so if you need parking you will need a relay - a basic Bosch type SPST works. maybe you can live without (manual park - trial & error).

Connect:

31 to Ground

Assuming normal speed is OK? - Ignore 53b (med), 53i (fast) - only one can be active at a time
Connect 53 (norm speed) via an SPDT switch (common) to ignition power (15) on one terminal (run) and connect the other terminal to your new park relay's 87 terminal (park)

This relay's 86 & 30 should go to ignition (15) via fuse, the 87 to your switch terminal and 85 to the 53a terminal on the park switch with the 31b terminal of the park switch connected to ground.

If you want more than one speed or if you want to just always run at a faster speed you need a different config. Running more than one speed isn't intuituve without a column switch.... e.g. you'd have to fiddle with more than one switch...

Alan

IcemanG17

this is one thing we intentionally left alone in the Estate...since many of the Lemons races are in the winter around here.....and having wipers without the "park" feature gets annoying FAST

Mike Simard

Since a relay is needed, how about using NC contacts for 31b (park) to 53(low speed). The relay coil switched hot by the toggle switch when wipers are on. The toggle switch could power any of the 3 speeds, when on it would be breaking the park/low speed circuit.

Brian, Lizard, Alan, I understand what you mean about keeping controls intuitive but I don't agree that a multi function wiper stalk is intuitive. I find them potentially confusing and in the way. In my personal controls theory, only one column switch should be present for lights if anything.
IMO, a clean steering column free of multi function switches allows better concentration when driving hard. I've driven many years and miles in 928s and can't tell you at a moments notice what all the stalks do, I didn't even realise we had 3 wiper speeds when starting this thread. Reaching for a toggle switch that I know the function of is much more enjoyable than running the owner's manual through my mind as I reach for what I hope will be the correct stalk while blasting down the track in the rain.

Thank you guys for the advice!

Alan

Mike - with just one toggle switch for operation I agree with you.. but if you require 2 or more switches for multiple speeds I don't agree at all...

I'm not exactly sure what you are proposing - remember the parking switch is low current and only the relay coil can be controlled by this switch to feed power to the slow speed 53 motor winding via the relay contacts it (may not park reliably at higher speed). This parking circuit is only active when ignition is on and wiper switch is off.

You can indeed select any single speed of operation for your run speed but will need a different switch config than I described for this...]

With just the same SPDT switch: switch Common to fused 15 supply, switch run position direct to 53b or 53i, and switch off/park position to relay coil 86, with relay coil 85 to ground via park switch as before.

Relay contacts: 30 is fed via fused 15 supply and 87 to motor 53 for parking speed operation.

Alan

Mike Simard

Are you sure that the parking switch can't handle current? The way I interperet the 928 schematic is that it does pass the motor current in it's normal configuration using the interval relay and I'm pretty sure other Bosch wiper motors do. Am I missing something?

The plan is to have a ST toggle turning wipers on high speed with parking being done by the low speed. I do have to keep myself from complicating that with silly ideas such as 2 speeds on a DT toggle, if I mention that again please bop me on the head. I already have the ST toggle in my car that I installed when I built it years ago with this idea in mind.

It would simplify wiring to do this with one relay like I described above but if I have to add a second relay to keep the park switch from handling current so be it. It's still going to be one simple wiper switch with one position

Alan

Mike - yes you are missing it (this is a common mode for other similar german cars - VW/Audi use intermittent relay to drive parking too).

The switch feeds the 15 power via relay terminal 53M to the switch 53e terminal and via the switch in the off mode to terminal 53 on switch and motor...

Its not intuitive - but remember the parking circuit is only active when the wiper switch is off... so 53a & 53 on the switch will not be connected at his time. 53s feeds the coil controller in the relay - thats the important thing to notice...

You only need one relay - as I wrote prev.

Alan

Mike Simard

By other cars I was thinking of old VWs without interval wipers. They appear to use the park switch to handle current from what I can tell. All of these wiper motors seem to use the same DIN numbering with the exception of the 928 having 53i for high speed. Should I look at the 928 wiper as fundamentaly different when wiring?

How about dynamic braking to stop the motor at it's stop point? Is this done by shorting the windings on the 928 wipers?

Thank you for your patience. If I were you I would explode by now!

Alan

Mike - the terminal ID numbers are a standard developed by Bosch (for DIN specs) and are used by others too - they relate to electrical functions not ratings. Porsche uses them on pretty much all items.

The stock config does include dynamic braking (thats the ground connection to 31b when parked) - but I don't think you will need it unless you run in fast speed...

It is possible to configure for it but its more wiring... If you wanted to use it you'd need to use the relay in SPDT mode inseatd of SPST.

If you wanted to anyway do it like this:

SPDT switch: switch Common to fused 15 supply, switch run position direct to 53b or 53i, and switch off/park position to park switch 53a and park switch 31b to relay coil 86 and to relay contact 87a. Relay coil 85 to ground, relay common 30 to motor 53 and relay 87 to the fused 15 supply.

Again I don't think you will need it - but no more hardware is needed to config this way.

Alan

drooman

@Alan
Reviving this relic I found while searching for wiper issues. My 84 wipers work in all aspects (intermittent, parking, etc) except that there is no high speed. Switch is getting power to 53i at the plug, and through the plug to the motor. Does this mean a break in the connection at/to the 53i brush inside the motor? or are there other electrical tests at the plug to confirm before pulling the motor?