MadaboutKitcars

Hi Robin,

This thread is a bit old now but I have had an afternoon trying to get my "park" to work and I've got brain ache.

I have the Lucas 14W motor and am using the BMW stalk. I have fast, slow and flick wipe working fine. But the park function is beating me.

Looking at your diagram pins 2 and 4 provide the park function. Assuming slow speed operation, 12v is applied to pin 5 via the stalk switch. There is also a permanent 12v on pin 4. For approx. 330 degrees of the main wiper drive gear that 12v on pin 4 is switched through to pin 2. Only when the drive gear is in the park segment of its rotation, the internal switch is depressed (open circuit) and the 12v is removed from pin 2.

In the absence of any wiring diagrams I have connected pins 2 an 5 (on your diagram) together. In slow speed operation, the slow speed switch on the stalk and the internal park switch are in parallel and are both closed except during the park segment of main wiper drive gear, when the park switch is open circuit. But because the two switches are in parallel the wipers are still on as a result of the 12v from the slow speed switch. (pin 5)

When the stalk switch is turned off that removes the 12v from that side of the parallel switches to the motor. However, the 12 from pin 4 via the park switch to pin 2 and then pin 5, ensures the motor will drive round to the park position. Once it reaches the park position, the park switch will become open circuit, removing the 12v at pin 2 (and pin 5) and the motor will stop. And that all seems to work just fine (with the drive gear removed and my finger acting as the cam on the drive gear!!)

However, with my finger still on the park switch, replicating the normal "rest" position, if I then switch the stalk switch to slow, the wiper fuse blows.

And that really confuses me. All I've got is two 12v switches in parallel. Each switched supply works fine independently but when I select slow speed from the park position the fuse blows.

Sorry for the long winded explanation. It probably needs reading a few times before it makes sense, but if it makes sense can you see any reason for the fuse blowing. I'm struggling........................!!

And then to confuse me even more I spoke to SVC this afternoon and they said that I should have 12v connected TO both pins 2 and 4. That didn't make any sense at all but in desperation I tried it. And blew the fuse.

Can anyone explain what is connected to the five pins. Not what they do, but whether they are supply or earth or where they are connected to.

Any help would be greatly appreciated because at the moment I'm thinking of swapping out the motor itself and that's a bit expensive if there' nothing wrong with it!!

Many thanks

Nigel

Hi Nigel,

I didn't use the stalk switch so I don't know, but i'm wondering if the BMW stalk switches to 'ground' rather than to B+ ? I think your wiper motor connections theory looks right to me.

...peter

Hi Peter,

You're back!! I haven't seen you on here for a while. Good to hear from you.

I built up my loom as I went along so I know I am switching +12v through to the 1st and 2nd speed terminals and the fact that they work independently indicates that I'm not picking up an earth there.

One thing I thought about this morning (and I know it shouldn't make any difference) is that the 12v on pin 4 and the switched 12v to pins 3 or 5 are both from the same fused supply. I'll try using separate supplies and see what happens............................

Nigel

It's too long ago to remember much detail but I think my original explanation was correct. All the park circuit does is apply power to the slow speed connection, as the wiper switch does, except it only applies it till the park position is reached. From you explanation it sounds like somehow you are shorting to ground using the park circuit.

I used the standard bmw loom complete with wiper relay which simplified things a bit.

Cheers, Robin

Hi Robin,

That's exactly what I am doing.

But I have drawn out the wiring diagram from the supply via the switch to the motor (using your diagram) and I can't work out where the earth is coming from.

It's interesting that you mention the standard loom and a "wiper relay". I found this circuit [url]www.Vitessesteve.co.uk[/url] and have wired up my wipers the same way and now they works just fine..................


wiperdiagram by MarlinBuild, on Flickr

It's a simple change over relay that isolates the wiper supply voltage from the park supply. It works, but for me, it still leaves the question Why??

But being pragmatic, it works, so forget it.............................!!