w124 power window issue

[jdulle]

I've got a problem with my power windows that is puzzling me. 1990 w124. I made the mistake of opening one of my windows this morning. Went down fine, but won't go up. As I press the button it will continue to go down but will not go up. The strange thing is that the passenger window is doing the same thing. Now they are both stuck part way down. I can hear it clicking in the convenience module under the rear seat when I press "up". I tried a different convenience module and no improvement. That module was able to raise the passenger window today as a test in the other car. So what could it be, both switches failed due to humidity? It wouldn't be wiring, correct, since they still go down? Also not fuses, right? I twisted those to make sure, both for the convenience module and the power windows. I have some extra switches but they are not the right ones, and the ones in my other w124 are a little harder to take out on account of the newer style sliding door console over the wood panel that houses switches.
Any ideas?

[jbach36]

I'm assuming there's a problem with your interior window regulator. To fix this, you have to take the door panel off. YouTube how to do it and read some articles.

Once that's off, take a look to see how that stuff on the inside is put together. I forget all the details but it will be pretty obvious what the problem is. Clips that are either broken or need to be lubed so they can slide easily. The old grease has turned into peanut butter at this point.

Not a fun job, but get to it, because it will be even less fun when you need to drive somewhere and it's raining. Plus if you don't fix it and keep playing with it to get the windows up (which it's NOT going to do since they're messed up), you can make things worse.

[jdulle]

I suppose it is either the switches or the regulators. I had the door panel off of the passenger side in the last 6 months and cleaned and greased everything. That window was working smoothly 3 weeks ago. The driver's door panel is the one I hadn't taken apart because that window had been working. I have the door panel off now, so will test with a drill battery to see if I can get the windows up. If it works I will also lube it so it keeps working. I may try holding the key in the lock position to see if that will raise the windows. I suppose if that works it has to be the switches, or resistance in wiring to switches?

[tyl604]

If this were my 81 300SD, I would say it is a broken sliding jaw. Not sure if your vehicle has the same regulator suspension raising-lowering system. May have been updated by 1990. Lots of info about broken sliding jaw here and easy to discard it as a solution.

[Steve12]

Hello!
Although it seems like both breakers could fail at the same time, it is quite unlikely. However, moisture or contact corrosion can cause problems. Try cleaning the contacts with alcohol or contact spray and see if that improves the situation. If you have extra switches, try installing them even if they don't fit perfectly to rule out a switch problem.
The problem could still be in the wiring. Check the wires leading to the power windows and the connections on the comfort module. Although you hear a clicking sound in the comfort module, this does not necessarily mean that the signal is reaching the window motors. Try powering the motors directly using a battery to see if they work both ways. If you are looking for bulk car accessories, you can look at the online marketplace globy
You mentioned checking the fuses, but it's also worth checking the relays associated with the power windows. Sometimes the problem may be a faulty relay that is not switching properly.

[Texasgeezer]

With two windows failing, I'd suspect the voltage and wiring going to the window control module. Possibly the related window relays behind the fuses ( might be A & F )


But to checkout the motors,
My first approach would be to remove the plugs to the ' comfort module '.

Find the two wires on the plugs that go to one of the failing windows.

Use 12 volts from a battery or battery charger and jump to those two wires. I'd use a battery charger since the voltage would probably be higher than a battery.

Window should either attempt to go up or down depending on polarity.

If you get proper movement reverse the 12v wires and see if the window goes in the opposite direction.

If you don't see proper movement. Remove door panel and find the terminal block where the control module wires connect to the window motor.

Separate the two window motor wires and do the same type test on that window motor.

That should test the electrical part of it from the control module. If the motor doesn't move the window I'd probably remove the motor and window mechanism next for further checkout.

Just my thoughts. But my brain is getting older and messes up from time to time.

The motors are pretty rugged. In my opinion if the motor works one direction, it is probably not the motor since the polarity changes and the motor wires and brushes stay the same to provide the required current for motor movement.

[jdulle]

Texasgeezer you were right. Both motors were fine. I tried using the "convenience" feature with the key in passenger door lock to close the windows. That worked, but left the sunroof with the rear lifted. So I checked some more fuses. Turned out it was fuse #2 (I think), that was another fuse for the convenience relay, and had some control over the windows and sunroof. I just twisted it and now all items work normally. Funny because I found both the window lift fuses and another fuse labelled convenience and twisted them and cleaned them and no improvement. At least now I have the drivers door card off so I can grease the tracks and gears.

[evranch]

The first thing I do with any European equipment with torpedo style fuses is pull them all out, polish the sockets, and replace them all with new ones. Sometimes on something like a tractor it makes more sense to replace the entire fuse box with a modern blade style box.

They are incredibly prone to corrosion because the fuse alloy is also used as a contact. Stop twisting them and toss them in the trash, $10 will save you a lot of mystery problems in the coming years.

[vstech]

ONLY USE GLASS FUSES WITH COPPER ELEMENTS.

[jdulle]

All the fuses in this car are new. I could only get the copper/bakelite fuses for 2 of the colors, but I will look again, because I bought another w124 that needs new fuses. I used a wire brush to clean them, and then put on dielectric grease. This doesn't seem to be good enough, so I am thinking of degreasing, sanding with ultra fine sandpaper, and replacing the non copper fuses. At least I know that most any electrical problem (that I have encountered so far) can be traced to those fuses.

[Sugar Bear]

Consider using a fiberglass brush to clean the fuse box vs sandpaper.