Rear window motor question

Have a new to me 1987 Cabrio 3.2 that works great but the rear windows are slow. Not exactly a novel problem.

I have removed the rear side vents, cleaned out the original 38 year old grease with a ton of degreaser and lubricated everything. The passenger side window is now good. The driver side rear window, well, not so much.

I am no electrical engineer, but the window gets a nice 13.5 v at the plug that connects to the motor with the car running when I hit the switch.

Contacts in the switches, fuse box, fuses and relay are all clean, no obvious evidence of burns or resistance. Just because I see full voltage, is that proof that the wiring is ok? Voltage drop tests disclose no material drops.

Down it moves slowly, up is a problem. If I pull on it, it creeps up.

I will probably try to remove the entire assembly and look at it on the bench. Do the motors wear out? Is there a substitute available if it is worn out or can it be rebuilt with brushes and bearings?

I am also not sure it is the motor - I would have thought it would not move at all if the motor has burned out

 

Read these threads, lots of info.
https://www.ferrarichat.com/forum/threads/mondial-rear-windows-stuck-in-down.339623/
https://www.ferrarichat.com/forum/threads/another-mondial-rear-window-stuck-down-help.302898/
The assembly seems to bind up in the "loops," I don't think it's possible to clean and lube the entire mechanism without removing it from the car.
Someone tried using a Volvo unit as replacement, but it involved a lot of fitting and adjustment, oem replacements are NLA as far as I know.
Alden
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Seems obvious, but make sure your battery is new and the alternator charging, as the windows being slow can be caused by the battery. My rear windows slowed, one more than ghe other, the alternator was failing and my new battery was in fact undercharged. Alternator rebuild solved the problems.

fyi, There is also an access panel in the wheel well where you can get some access in there to clean and lube the slider on the central square channel. I recall removing some things to get to that panel, one side was more accessable than the other. You can get at the comnecting plug as well.

I think you need to measure current under load to determine wiring problems. Volts doesnt tell the full story.

Remove the switches and spray inside with deoxit contact enhancer and actuate the switches a hundred times. Those switches have small contacts inside and small invisible surface corrosion can affect their function.

There are no simple plug and play repairs or replacements for those motors. But if they are working at all, cleaning switches and connectors seems to solve for things.

 

By coincidence, my right side rear window stopped working yesterday. I removed the side strakes and black access panel today. I was able to get at the wiring easily. Tried running 12 volts directly from the battery, no movement, but I can hear the motor running, but I could hear it running when I used the switch too.
I guess I am going to try removing the glass and regulator assembly from the top, window is in the up position about one inch from the top.
Pics of what I could see.
Alden
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Thanks for the threads. Some interesting reading. I am not 100% certain I want to start buying Volvo bits. That removal is more complex than anticipated. Just removing the window from the lifter mechanism inside the car looks challenging. Installation looks worse.

I think I will keep on the cleaning and lubricating path for the moment. How do I check to see whether the current under load is the problem?

 

I bought a pair of the Volvo units, $137 on eBay, left and right, not in a hurry to dive into this project because it's top-up weather here in Florida (too hot!) and my window is in the up position, I'll probably tackle it once winter gets here and I want to put the top down.
Alden
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I am far from an electrical person, but I would do the following. With the motor disconnected, measure the ohms at the two leads to the motor. I am not sure what normal resistence should be, but probably not very high if the motor windings are ok. Some degradation in the windings would certainly cause a slow movement. Maybe someone can confirm an ohm reading for a working window, maybe the one you say is moving faster?

To do a hillbilly load test, you can connect an incandecsent brake light bulb to the harness that plugs into the motor and see if when you switch the switch on does the bulb burn nice and bright. That bulb draws about two amps, so you would know you are getting at least that amp under load. The motor probably takes more amps, but if at least the two amps you are probably getting an indication that the switch and wires are carrying some meaningful current. Maybe there is a test tool or approach others are more familiar with. The modern led test lights dont require enough amps to light up be that diagnostic.

Try the switch on the window that works on the slow one, to also rule out the switch being the problem.

These are low effort checks, so even if am giving useless advice, first do no harm! I am still suspicious of the battery and switches with slow but still moving windows.

 

I attempted the Volvo mechanism transplant and had absolutely no luck getting the mechanism to fit into the car body, even after the required modifications. When I contacted the person who claimed this was doable, all I got was ancient threads and pics that I already had, and claims of "forgetting" how it all works. Save your money and weeks of frustration. If someone else out there can make this work, I will gladly eat crow and attempt it yet again, but I'm dubious about this ever really being a fix.

 

Great Scott, yeah I read all those threads although the pictures were from photo bucket and missing because the thread was so old, well I have the regulators coming and I'm willing to give it a shot. Shot. I did see one video that someone posted of the left side window operating with the Volvo regulator installed, and it was working very well, so not doubting you but I think it may be possible somehow, any other information about how you tried to get the unit to fit would be helpful.
I'm also going to contact Stephan at Red Bay and see if he has any regulators in stock.
I also was interested in Stefan's solution of attaching a leather strap to the window to pull it up into place and then locking it with a Tenax clip.
Was the problem that you physically could not get it placed into the body, or you had difficulty bolting it down?
Alden

 

Thanks. My efforts will go into cleaning the mechanism of the one sticky window. I can put my gauge in series between the motor and the switch to see how much current it draws, but other than the rear window on the other side, (which works better but not perfect) there is not much to compare it to. I note that all windows work off of one common relay and fuse. The front windows are really fast and work well. So that is something eliminated.

The car is quite reliable, comfortable and easy to use, the problem is that taking it on a long road trip would mean putting the top up and down a fair bit. The idea of getting stuck far from home with a lowered rear window in a rainstorm does not sound like fun.

 

It might be worth it to make up a couple of plexiglass panels and take them with you so that you can seal off the window area in case this happens.
Alden
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Another solution I mentioned above was offered by Stephan, a leather strap you could attach to the bottom of the window, pull up and lock to a Tenax fastener.
Alden
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Video the Volvo regulator working well on the left rear window of this Mondial.
Alden

 

Its been a couple of years since I attempted this, but IIRC, I had issues just getting the regulator assembly to fit into the cavity in the correct position to make everything work. It just didn't want to go where it needed to go. I contacted the original poster of all the stuff out there, but he had sold his car, didn't have some of the needed photos anymore, and couldn't provide much in the way of details. I whole heartedly applaud your attempt, and hope you get it to operate for all of our benefit. I am certainly not a Foose level fabricator, so my skills may have been lacking in getting everything set up. I have been exploring finding a better lubricant for the original mechanism than white lithium grease. Seems like there must be something more slippery out there that will allow the cable to make those crazy bends in the regulator a bit easier.

 

I think the main problem is finding a way to secure the motor, correct ? I'm sure there's a way to fabricate a bracket so that it'll bolt in, we'll see!
Alden

 

https://www.prolabtechnolub.com/en/products/product-details/cd-1000/#:~:text=PROLAB's CD-1000 with antifriction,, hinges, and seized mechanisms.

I think the problem is that in tough environments, you need to reapply lubricant fairly regularly. If Ferrari's "major service" recommendations included removing and greasing the window mechanisms as frequently as timing belt changes, they would probably last forever!

I am surprised that the original manufacturer of these mechanisms did not make them for other cars, and something close to fitting should be more readily available. I recall people saying a Fiat may have used them, which of course would make sense, but no one seems to have successfully cracked a corss reference code I am aware of. Where are the Chinese knock of manufacturers when you actually need them? Everyone of these Mondial cabriolet's will need a window motor at some point, that has to be a big enough market for a reproduction to see an economic case even if the prices would necessarily be very high.

 

I know GT Car Parts is selling stronger motors for the door windows, but so far no luck on the rears. I take mine apart and clean and lube them every spring and they still are slow and noisy. The window sweep on the outside DOES make a difference as to how well they move as well. Take that trim piece off and the windows seem to act much more normally. Maybe just a thinner or smaller rubber sweep would also help. The drag seems a bit excessive.

 

So, the mechanism was cleaned thoroughly and greased with lithium grease. Small improvement, but when I connect the terminals directly to a car battery, it moves up and d0wn like new. When I plug the motor back in to the harness, the motor moves 3/4 the way up then freezes. No up, no down. I wait a few minutes, then it moves a little again. Until it freezes again.

It seems that there is high resistance somewhere, when it heats up, the resistance goes up and the motor stops. Wait a bit and it cools down and works a little bit.

Switch is ok. Clean and no resistance. Connector at the motor is ok. Fuse is ok, relay was replaced without effect. Battery terminals and kills switch are ok. Connectors at the fusebox are tight, clean and without burn marks.

How does a relay even work with switching polarity to move the window up or down?

Is there a ground somewhere? I doubt it, the polarity just reverses to raise or lower the window. I have the factory shop manual, but there are no wiring diagrams in the manual.

Anything I am overlooking? If it was the motor, swapping the source would not fix it.

 

Everyone needs to get a copy of Afterburner's full color electrical drawings for our cars, here's the page having to do with the rear windows, thanks Afterburner for this wonderful work!
Alden
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Thanks! That is very helpful. Where can I get a complete copy?

I see all the components as I understand them. But what is that thing in the middle I have circled - they seem like separate relay boxes? Are there 2 of them? Where in the car are they located? Seems like a good place to look, along with that one lonely connector between the switches and the relay box (if that is what it is).
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@afterburner
"Afterburner" is a member here, contact him.

The part you have circled is the dash switches, the one on the top left is the rear window lockout switch. The panel to the right of that that you did circle are the indicator lights in the center stack. The lockout light lights up when you push the button to lock the rear windows.
Alden

 

Correction:"the panel on the right that you did NOT circle are the indicator lights."
Alden

 

Is there a difference between a ‘quarter glass’ and a ‘rear quarter glass’? The diagram is a bit unclear.

I expect a series of connectors between the battery and the a window motors. Something must be corroded somewhere.

 

No, they are the same "rear glass" panels.
ald5