1987 300td none of my windows working - PeachParts Mercedes-Benz Forum

240dddd · #1 01-26-2019, 11:44 PM

Trying to sort out some issues on a new-to-me 1987 300TD.

None of the power windows are working. I replaced the two fuses for the windows and the front passenger worked temporarily (i.e. a couple of times) but has stopped working.

Today I took out all the window switches and put them back just to see if that might do anything. It didn't, but I noticed that even with the keys out and the lights off the backlights of the buttons were still on. Not as bright as when the headlight switch is turned on, but dimly still on. Not sure what that's about or if it's related.

Is there somewhere I should be checking besides the fuses that would affect the functioning of all the windows?

dlssmith · #2 01-27-2019, 12:42 AM

If you can, peel back the accordion boot between the door and frame where the wires pass. Sometimes you can tell if the wires are broken as they often break right there. Though I wouldn't expect all 4 to break. You've got a short somewhere - those little lights should not be on when the key is out and the headlight switch is off. Any other electrical gremlins?

Maximan1 · #3 01-27-2019, 01:08 AM

When the windows worked temporarily, did they move at normal speed or were they slow? Maybe there is a lot of old solidified grease slowing down the regulator, which causes the fuses to blow.

Also would check the window run channels for old grease slowing hindering window operation. This sounds mechanical to me only because you said the windows worked temporarily after you replaced the fuses.

As for the light staying on, do you have LEDs installed in the back lighting? Not super familiar with the wiring on W124s, but on my W123 I have LED brake lights and they stay dimly lit when the car is running but the brakes are not applied.

240dddd · #4 01-27-2019, 08:05 PM

I'll look into the wires going into the door, however I also find it odd that none of them work, i.e. there isn't even a clicking noise on any of the doors as if their motors are trying to work.

It was only the front passenger window that temporarily worked, and it worked fine for the brief time it was working (i.e. didn't have any struggles going up and down).

I had disabled the alarm by unplugging the black box in the passenger foot well. I plugged it back in to see if that was the problem. It wasn't.

The more I work on this car I'm finding all sorts of electrical gremlins. The windshield wiper was working then stopped. If the alarm isn't disabled I have to take out the 'C' fuse because it constantly goes off. The electric close assist in the trunk intermittently starts buzzing. The door locks sort of work. The seatbelt warning light is always blinking.

I think the PO replaced the dashboard, so I'm concerned he may have mucked something up while doing that job. It's unfortunate because the drive train of the car is quite good.

dlssmith · #5 01-29-2019, 11:36 PM

I would be checking grounds everywhere possible starting with the most obvious from the battery to the frame. The oddest things happen due to corroded grounds.

240dddd · #6 02-02-2019, 02:44 AM

I've cleaned several of the ground locations without any progress:

Driver side headlight (W9)
ABS bracket (W14)
Front dome lamp (W4)
Center Console (W12)
Two grounds points on passenger side shock tower (W10 I think)
Rear Wheel well grounds (W6 and W7)
Rear Hatch grounds (W8, although there are two in my rear hatch, only one shown in the w124-zone diagrams)

Still have several to check, but so far no impact on the window functionality.

As I mentioned before, the center console button lights are always on dimly. I noticed that the license plate lights are also always on dimly. I also noticed that when I unplug the three prong plug in the rear hatch to the right of the close assist (toward the passenger side) those lights go out. I think all those systems are on fuse 3. Not sure what to do about it yet.

Also I noticed that there is an empty plug block in the driver side bottom of the rear hatch. Anybody know what this is for:

jay_bob · #7 02-02-2019, 08:27 AM

That plug I believe is for the intermittent wiper control relay in the rear window.

Power windows on the 124 run through a relay in the main fuse box.

There are two three pin connector on the lock mechanisms. One is for is the sensing for the central locking system and the other for the alarm.

I would look under the passenger foot well carpet for the alarm box and see if it has been unplugged. If not I recommend unplugging it. The common thread between the sensing switch and the parking lights is the alarm box. The alarm box switches voltage to the parking lights to make them blink when the alarm is triggered.

Do you have access to the factory manuals and wiring manuals?
http://w124-zone.com/downloads/MB%20CD/W124/Main.html
Be sure to go through the drop down for the wiring diagrams as there are several addendums. If you have access to full Adobe Acrobat I would take the files, strip out the pages for the models that don’t apply to you, and paste in the addendums in the right place. That will make it much easier to follow.

Pulling a 124 dash is not terribly difficult. The procedure is on that website. Just be patient as a lot of the things are going to be brittle from being 32 years old.

240dddd · #8 02-05-2019, 05:49 PM

I had already disabled the alarm under the passenger footwell.

The other night I got underneath the car and cleaned up the connections for the large grounding strap located near the footwell for the driver. After cleaning that the passenger window started working again, but just the passenger window.

dlssmith · #9 02-07-2019, 09:05 AM

Sometimes the fuses corrode a bit and work intermittently. Small chance of a weak contact there. At one point, I took all of my fuses out of the 87 and cleaned the ends with good rub on a cotton cloth. Some people recommend replacing fuses proactively. Not sure if that's useful, but its easy to try.

jbach36 · #10 02-08-2019, 04:03 PM

On my W124 the switches themselves go bad and need to be replaced.

Get rid of the old pitted metal fuses and get new copper ones. They're not very much.

dlssmith · #11 02-08-2019, 04:11 PM

Quote:

Originally Posted by jbach36

On my W124 the switches themselves go bad and need to be replaced.

Get rid of the old pitted metal fuses and get new copper ones. They're not very much.

I concur with replacement of the switches. They aren't too expensive and I finally got kind of fed up with trying to clean mine (they can be disassembled carefully) and just replaced them.

dieseldiehard · #12 02-08-2019, 05:23 PM

Quote:

Originally Posted by dlssmith

Sometimes the fuses corrode a bit and work intermittently. Small chance of a weak contact there. At one point, I took all of my fuses out of the 87 and cleaned the ends with good rub on a cotton cloth. Some people recommend replacing fuses proactively. Not sure if that's useful, but its easy to try.

about those old Mercedes fuses!
I have seen mote than a few instances of something not working in a MB due to lousy German fuses!! They finally went to ATC blade fuses after all these years - thanks to Stuttgart for that

I've found contacts in the fusebox like what is being discussed here were making poor contact despite changing to new fuses.
Using a drill bit I twirl the point against the place on the contacts where they touch the fuse, just enough pressure to remove a slight layer of corrosion and they appeared bright again.
I used a small drill bit around 3/16" as I recall and during the process disconnect the battery. A shot of compressed air will clean up the fusebox afterwards.
Old German fuses (like pre-1980) were made of lead and being soft it sometimes wears thru due to vibration and separates at the junction of the spring contact.
New fuses being supplied are aluminum, sometimes colored to appear like copper.

dieseldiehard · #13 02-08-2019, 05:33 PM

Quote:

Originally Posted by dlssmith

If you can, peel back the accordion boot between the door and frame where the wires pass. Sometimes you can tell if the wires are broken as they often break right there. Though I wouldn't expect all 4 to break. You've got a short somewhere - those little lights should not be on when the key is out and the headlight switch is off. Any other electrical gremlins?

I echo dlssmith's comments. The wiring in W124's is notorious for cracking, as is wiring in the Bosch/Hella headlights of W210 cars (BTDT!)
I had a window lifter problem which was traced to poor insulation in the R Rear door, when the rubber boot was peeled back the wires were visibly showing copper! Instead of ordering a replacement harness (which may no longer be available?) I spliced new wires from point to point and I used high quality wire and I soldered the joints and covered them with heat shrink tubing.
Come to think of it, I have an intermittent seat in my '95 E320 and I am afraid its most likely caused by the wires in the rubber boot.
What with frequent opening and closing the wire gets stressed, and that lousy German insulation gets all chafed and crumbles off.
Darned I wish they had used better quality materials in these fine cars. Makes me wish I had a Lexus!

pwogaman · #14 02-10-2019, 10:55 PM

Check Relay F: K4 for prior to 1990; K24 thereafter.

Convenience Relay Module 001-542-78-19, 0015427819, W0133-171526. Pictures of Repair

240dddd · #15 02-18-2019, 01:02 PM

Thanks for all the great suggestions here. I haven't had a chance to work on it for few weeks but will update here as I make progress and/or find anything of interest.

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