512TR window regulator control

My driver's side 1994 512TR window ceased working. The passenger side works fine. The switch is good, I can hear the relay clicking in the window regulator control unit behind the fuse box, and I swapped the switch to a brand new unit without change. I pulled the door panel off and checked voltage to the motor. When the switch is depressed either up or down, the window motor makes a "clunk" noise and voltage spikes momentarily to 6.8 volts and then is gone.
Nothing moves.
Questions:
1. Is the window regulator control unit simply a relay box with separate relays for each side
2. Is there a power window relay on the fuse board that may be bad?
3. Has anyone ever taken the window regulator control unit apart? Can it be repaired?
4. The heavy black plastic water shield under the door panel crumbled when I tried to remove it (21 years in the Florida heat will cook most things). Can I simply replace it with heavy clear plastic sheeting, or is there something better (it resembles tar paper).

I assume the door switch controls a relay in the window regulator control unit that then sends current to the window motor, or is there a more circuitous and typical Ferrari route?
Thanks.

 

Hi Mel and all others who responded. Yes, Mel, I printed out your write-up and had it with me during disassembly. The photos I find are invaluable during such products and it helped me to get the power window assembly out without complications.

Regarding the motor, are the two wires 12v pos and neg and does the switch/relay assembly merely swap pos and neg to make the window go up or down OR is the motor grounded through the frame and does the switch/relay assembly merely send 12V to one wire at a time to make the window move?

Mt power window unit looks brand new - nothing outwardly rusty, kinked or bent. I will bench test the motor tomorrow and post the results.

The door speaker is a MB Quartz unit and looks aftermarket. I know the first owner (Sheik Abdus Koreshi) sent the car to a Ft Lauderdale stereo shop when new for alarm and stereo install. I have a previous post of the horrendous hack job they did on the gorgeous Italian wiring harnesses. I know the 512TR's did not come with a stereo head unit installed - but did they have speakers in the doors from the factory? And, if so, anyone know the type/brand?

 

Dear Lear60man:
Kinda right. It was the motor that was frozen. See below.

 

Turbo-joe:
Kinda right also. I had a plus AND a minus problem. See below.

 

Mel:
Yes and no. Yes, the power (+ and -) are simply reversed to make the motor rotate clockwise or counter-clockwise and make the window go up or down, but no, the motor was not perfect. (see below).

 

TF308: Correct on both counts. Here is what I found next to the speaker. Is this stock? And what is the soft, round, orange thingie behind the speaker?
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First I got a battery and applied 12v to the two wires coming out of the motor - NADA. I then took the motor off of the gearbox and the flexible screw mechanism. A bit of fusty liquid came out. Not a good sign. The mechanism could be turned by hand and the plate that attaches to the window went up and down easily.
The MOTOR was the culprit.

After taking apart the motor I found the commutator (the part that the brushes contact) was pretty fouled. There was some rust on the inside of the case, but everything seemed otherwise intact.
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Nothing seemed frozen, so I cleaned up all parts with electrical contact cleaner, WD-40, some long q-tips and a scotch-brite pad. The brushes looked good.
The white plastic piece holds the brushes and there are two springs and two little holders that keep the springs in place. They pry out and push in. The brushes themselves are attached to the white plastic piece by a wire. I think it can all be dis-assembled, but I did not see the need. The little white plastic plug goes in the hole in the back of the motor case (there are two).
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After that, I greased up everything that moved. The ends of the armature shaft have pieces of hard plastic for less friction. I shoved a good amount of grease into the gearbox and made a new gasket by the careful application of some RTV silicone. Then just screw everything back together.

When re-assembling the motor, first fit the white plastic piece over the armature, then insert the springs and holders, and then slide the whole assembly into the motor case.
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I greased up the flexible screw mechanism as well as the track and guide. A quick test with the spare battery and voila! everything moved in perfect harmony.

The entire mechanism is then re-inserted into the door. When inserting the mechanism, it is helpful to have a buddy hold the window glass in the uppermost position, so as to give more room and avoid scratches.

Once in place, hook up the wires and confirm movement using the switch (it did). Raise the window to the uppermost position with the window mechanism loosely attached to the window. You will have to play with the window to find the optimal position of the glass (the position of least resistance or friction when raising and lowering. The big bottom attachment bolt for the power window unit can be adjusted in or out to further optimize positioning.

Right now the window slides up and down much quicker than before. Tomorrow I will re-attach the inner watershield and fashion a new outer watershield to replace the crumbly material removed earlier (cooked by 22 years in the Florida heat), and then re-assemble the leather panels and I'll be ready for a Ferrari Club drive on Sunday and a trip to the 12 hour race at Sebring on Wednesday (after a wash and wax).

Thanks to all who contributed to this thread (especially Mel).
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As I am putting the door back together, I need to know the function of the inner black plastic sheet. Ddid it cover the motor, go between the window glass and motor assembly, or just act as another moisture shield between the leather door panel and the rest of the door mechanisms. If I know why it exists, then maybe I can put mine back in the correct spot (anyone have photos?).

 

Thanks, Tim, that makes sense now. The photos really help.