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Discussion Starter #1
Hello,

I am looking at fixing an issue with the windows not working on the car. My drivers door window works no issue up and down. I moved the switch around to the other 3 windows but they do not work at all. My front passengers side window switch will work going up on the drivers door but not down. I know for sure that I need to replace the switch.

As I understand the back switches are on a circuit, as in if the switches in the back doors are faulty then the switches in the front will not work.

Questions:

1. As I understand there are two fuses for windows on the car. Is it as simple as one fuse controls the drivers door and the rest are on that other fuse that might be faulty?
2. Whats the chances of the window regulators being faulty in all the passenger doors?

Child lock was not on either However I did put it on and tested with it in the on position just to make sure.
Sunroof works without issue Not sure if that matters with this care or not.
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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What year/model is your W124?
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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On an '88, the switches operate the window motors directly rather than via a convenience module as in later cars. There are two fuses - one does the left windows and one does the right. If you have movement of any kind on both sides, both fuses are good.

Window movement in one direction only is almost always a switch failure.

Yes, for the rear windows, if the front set of rear window switches is bad or missing, the rear, rear-window switches will not function either. Also check the rear window safety switch - if this is bad, the rear, rear-window switches will also not function.

If the switches and fuses are good, you may have a break in the wiring that passes from the body to the door or a bad motor in the regulator.
 

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Discussion Starter #5
On an '88, the switches operate the window motors directly rather than via a convenience module as in later cars. There are two fuses - one does the left windows and one does the right. If you have movement of any kind on both sides, both fuses are good.

Window movement in one direction only is almost always a switch failure.

Yes, for the rear windows, if the front set of rear window switches is bad or missing, the rear, rear-window switches will not function either. Also check the rear window safety switch - if this is bad, the rear, rear-window switches will also not function.

If the switches and fuses are good, you may have a break in the wiring that passes from the body to the door or a bad motor in the regulator.

Yea for sure one of the window switches is faulty. Since a left side window works that means the fuse that controls the left side windows is okay. Do you know which fuse controls the right side windows?

Rear safety switch? This is different from the child lock switch at the window switch controls?
 

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Discussion Starter #6
I moved the RR switch to the FR and now both the front windows function. This just leaves the two rears not working now.


Are all the switches in these cars the same or are the switches in the rear doors actually different?
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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All of the switches are electrically the same, but I'm not sure about them mechanically.
 

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Discussion Starter #8
I tested a good switch on the back windows and I can hear the back windows making a clicking sound but not actually rolling down. I was curious to know if the switches are the same because if they are that way I can swap a working switch from the front into the on the back doors and see if they roll down at that point.
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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If you hear a clicking sound with known good switch, more than likely the motor/regulator is bad. Also, turn on the overhead light and see if it dims slightly when you press up or down on the back door. If it does, then you are getting a heavy current draw which is indicative of a frozen motor/regulator.
 

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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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Rear safety switch? This is different from the child lock switch at the window switch controls?
We are talking about the same thing. MB calls it the "rear safety switch" in their documentation.
 

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Discussion Starter #12
I will double check and make sure I am certain it’s the regulator. I’m guessing it is not that hard of a job to do?
 

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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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Mine had similar symptoms, at some point the motor was making some noise as if it was trying to close and would not move, sometimes. Other times nothing.
Would open but not close, intermittently. The wire that was going thru the rubber elbow at the door had snapped but was barely touching.

Make sure your wires are in tact by tugging on them individually.....
 

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If you find the wires intact, the motor is the next suspect. They freeze up if left unused for long periods. They can be disassembled and cleaned but you have to assemble them with the utmost care because alignment is critical. They will be noisey once assembled if not perfectly aligned. Bottom line though is that you can usually disassemble and restore these window motors to operation if you are handy and have the time.
 

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Discussion Starter #15
If you hear a clicking sound with known good switch, more than likely the motor/regulator is bad. Also, turn on the overhead light and see if it dims slightly when you press up or down on the back door. If it does, then you are getting a heavy current draw which is indicative of a frozen motor/regulator.
I checked and the lights do dim when you hit the button. I am going to go with regulators are bad. I will look at replacing these and see if that resolves this problem.

If you find the wires intact, the motor is the next suspect. They freeze up if left unused for long periods. They can be disassembled and cleaned but you have to assemble them with the utmost care because alignment is critical. They will be noisey once assembled if not perfectly aligned. Bottom line though is that you can usually disassemble and restore these window motors to operation if you are handy and have the time.
Does cleaning the regulator all it take to fix them?
 

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Service all the door regulators,, and only way you can do this is by removing the door cards to inspect them , and rectify the problems your having . More than not its a simple job to find the culprit .Spot of oil ,,or a dab o grease helps the parts move .Never had the reason to strip out my back ones they run on cable wires .Fronts are on levers .
 
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