Rear windows won't work - PeachParts Mercedes-Benz Forum

lt1fire · #1 12-20-2011, 06:02 PM

Ok my rear windows won't go down on my 87 300SDL.
It was like this when I bought it and the previous owner though it happened when he spilled some coffee on the center console.
The second day I had it the front passenger side one also stopped working but I found out that that was because of a blown fuse.
I checked the switches and they will both make the front windows go up and down when inserted into those blocks.... could the blocks go bad???I couldn't find a fuse for the rear windows so i'm guessing they are tied into the front ones.

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jbach36 · #2 12-20-2011, 06:35 PM

This is not advice, just a guess....

When you have a remote control for a tv, etc., sometimes they get a bit of that battery acid on them, or even oils from your fingers on the AA battery terminals can make them not give power. So you can use a small fingernail file to scratch that off the terminals or contacts, and it will sometimes then make good contact, and your remote control will work once again.

It's possible that's what this area needs as well. Maybe the coffee stains are preventing proper electrical contact. Try scraping the contacts with anything that will rough them up some.

Good luck.

lt1fire · #3 12-20-2011, 06:50 PM

Quote:

Originally Posted by jbach36

This is not advice, just a guess....

When you have a remote control for a tv, etc., sometimes they get a bit of that battery acid on them, or even oils from your fingers on the AA battery terminals can make them not give power. So you can use a small fingernail file to scratch that off the terminals or contacts, and it will sometimes then make good contact, and your remote control will work once again.

It's possible that's what this area needs as well. Maybe the coffee stains are preventing proper electrical contact. Try scraping the contacts with anything that will rough them up some.

Good luck.

The switches will work in the front blocks though.
Maybe the female contacts in the rear blocks are gummed up though. got to find something to take a look down in there.

Brian Carlton · #4 12-20-2011, 06:57 PM

Do the switches on the doors operate the windows?

lt1fire · #5 12-20-2011, 07:14 PM

Quote:

Originally Posted by Brian Carlton

Do the switches on the doors operate the windows?

Thats a good point that I forgot to include in the first post. No they don't.
Which to me would normally mean a fuse or a relay but as far as I can tell the relay controls all 4 and there are 2 fuses for the 4 windows.

Brian Carlton · #6 12-20-2011, 07:29 PM

Quote:

Originally Posted by lt1fire

Thats a good point that I forgot to include in the first post. No they don't.
Which to me would normally mean a fuse or a relay but as far as I can tell the relay controls all 4 and there are 2 fuses for the 4 windows.

Pull out the LR switch in the console and find sockets 1,2, and 3 in the plug.

Check for 12V on socket 3..........that's the first requirement. The voltage comes from fuse "d".

If you have voltage on socket 3, jump 3 to both 1 and 2, simultaneously.

Attempt to open the LR window with the switch on the LR door. BE SURE THE SAFETY SWITCH IS NOT LOCKING OUT THE TWO REAR WINDOWS. Try it in both positions.

Report back.

jonbobshinigin · #7 12-20-2011, 07:34 PM

Pull the rubber piece off in the door jam where the wires run through and see if there is any breakage in the circuit. Twas the case for my 124...

MarkM · #8 12-21-2011, 07:43 PM

Quote:

Originally Posted by jonbobshinigin

Pull the rubber piece off in the door jam where the wires run through and see if there is any breakage in the circuit. Twas the case for my 124...

Ditto....In the two 123's I have had, I needed to replace a couple of wires in the window circuit where they pass through the rubber flex sleeve from the central pillar into the rear door....a couple of those wires are real prone to cracking with age causing short in the circuit.

Mark

Brian Carlton · #9 12-21-2011, 07:49 PM

Quote:

Originally Posted by MarkM

Ditto....In the two 123's I have had, I needed to replace a couple of wires in the window circuit where they pass through the rubber flex sleeve from the central pillar into the rear door....a couple of those wires are real prone to cracking with age causing short in the circuit.

Mark

..........both rear windows suffering the identical fate...........

MarkM · #10 12-26-2011, 04:49 PM

Quote:

Originally Posted by Brian Carlton

..........both rear windows suffering the identical fate...........

True this is unlikely, however, based on my experience, if wires have degraded in one door harness, they are also degraded in the other. (there are only 2 or 3 wires in that harness prone to serious degradation...I mean real drying and cracking and insulation coming completely off the wires). While it is unlikely that this is a "coincidental" cause of both windows not operating, I would not rule it out.

An easy potential check on this is this...while the car is parked, open rear doors back and forth to various positions and try operating the windows several times in various positions using the front console switches. If the cause is a short in that harness, you may be able to temporarily eliminate the short by opening doors to various positions.