Zagato Rear Window Motor Electrics

[Rog]

Could someone explain how the electrical circuit works on the rear hatch of a Fulvia Zagato please?

There's a SWITCH on the dash (UP to raise hatch, DOWN to lower). As I understand it, 1 hot wire (Black) comes in with 3 wires coming out of it....see attached pic. They're colored : white, brown and grey.

Those 3 wires go straight to the motor - second pic....

My understanding is that when 1 of those wires (Brown) coming into the motor gets 12v then the motor will turn one way....then the when switch goes the other way, the White wire gets 12v and it turns the other way....

The motor seems to behave itself in one direction....not so good the other way....but maybe Im doing something wrong when I test it....

What is happening here? Are these circuits somehow switching the polarity of the power going to the motor to switch its direction?
Any help welcome!
thanks
rog.

[lancialulu]

If you pull the switch from the dash and check its logic it is doing what you say. Problem is the contacts carbonise. You can dismantle the switch with absolute care to clean the contacts but be warned easy to lose small springs and bras fingers... Contact cleaner only works for a short time....

[Rog]

Thanks Tim.....

If I want to test the motor in isolation (take the switch out the equation)....then Ive got those 3 wires going into it (Brown, White & Grey)....

Would I connect power to the GREY going into motor, then if I add 12v power to the BROWN it should turn one way? then if I put 12v to the WHITE the motor would turn other way (But GREY always has 12v)??

[nistri]

The motor will start moving up and then stop if the 2 end-of-run switches (connected to the motor at the back) work fine (same for coming down). These are mechanical switches and if worn they can be replaced. Andrea

[Rog]

Thanks Andrea
The limit switches seem to be doing there job....so that part is okay. My problem seems to be the motor itself....which I dont think is original. It only has the 2 wires going to it.....the original has 3 (including the GREY....mine just has the BROWN and WHITE connected).
Do you have a picture or can you confirm that?

The switch seems to be behaving too : if you push it up you get 12v to the circuit raising the window and vice versa for the other "down" circuit...

[nistri]

To activate the motor, it needs a good earth. Is this present? I repaired mine a few years ago and ufortunately I don't recall the wiring now, however in general on the Fulvia electrical items are always connected to (+) and are activated when a switch goes to earth. I can check the wiring diagram if you don't have one handy, Andrea

[Rog]

If you had a moment to take a picture of your motor and the way its wired, that would be extremely helpful...
Do you have 3 wires plus the earth to yours ?

Mine does seem to be earthed - but it doesnt seem to be earthing back through the switch on the dash (as your comment would imply).....
Not sure if its the original motor, so trying to figure out that out

[nistri]

It is not easy to take a picture with the motor in the car. There are red (two), white and brown wires that I tried to photograph but so far my camera is unfortunately giving trouble to download the images, I will send them to you once I manage to solve this problem. Perhaps you can trace the connections using the wiring diagram of the car, Andrea

[nistri]

pics attached

[nistri]

one more

[Rog]

Thanks Andrea
The original wiring diagram doesn’t show the RED wires but it’s still very helpful to see
Thank you!

[Spider2]

Hi
I have a problem with my rear window motor as well. It works sometimes slowly.  I think it is a voltage problem.
Battery voltage. 12.5v
Fuse box.           12.3v
Switch output.    11.3v
Motor.                10.3v

I guess the motor does not like 10.8 volts but it does not work with engine running either although I have not tested the voltages with the generator on line. Biggest voltage drop is through the switch
So what is the cure?
1/ new switch:  Do not think they are available??
2/ rebuild switch. Full of perils, I have read
3/ modify motor to like 10volts?
4/ Put a relay in. Where is there 12+ bolts at the rear of the car,?
The grey wire from the motor to the switch has been disconnected with a PO labelling it ‘No Use’. That sounds Italian.
Help would be appreciated.

Thanks
Simon.

[Rog]

Hi Simon -

I’ve been discussing this issue with a number of people.
The general consensus is that installing relays is a good plan - by doing that you’re removing the ampage (necessary to operate the hatch motor) going through the actual switch...
That switch is prone to burning out - the contacts becoming carbonized by the amps going directly through the switch.

If you’re dealing with a series 1 car then you’ve got 3 wires going back to the switch - the GREY (+ve 12 volts for both UP and DOWN) and then either +ve 12 volts coming from either WHITE  or BROWN depending on if you’re engaging UP or DOWN.

The basic idea is to put another larger +12volt connection back there (ie. Add a 6 gauge wire or something) coming from the battery....then use that new power source to drive the motor. You’d use the original wiring to operate three relays - each pulling power off the new source to actually drive the motor.

Make sense ?
Rog.

[lancialulu]

This philosophy is used to imorove the 1600 electric door window function. The circuitry has been detailed in a VivaLancia article last year (sorry cannot recall which issue).

[Spider2]

Thanks Rog. Yes a series 1 and yes all very logical and I think I understand it. However......... my grey wire from the motor has always been disconnected. It used to work badly but now not at all. In your post you mention the grey wire as +ve. Is that correct if the brown and white are also +ve?  I say the grey wire has always been disconnected but perhaps it just became disconnected when I pulled the carpet away.
I have a 4th black wire coming out of the motor with a a brass ring on the end. I am guessing this is an earth but a PO has written a note on it say ‘NO USE’
If my motor is toast can I use a series 2 motor?

Cheers