Hello,

After 5 years of dealing with non functional rear windows on my 1985 300TD, I decided to tackle the project. I found some less bent rear regulators at a salvage yard, and straightened them and installed them in the car.

Here is the issue, I am not getting any power to the drivers side rear door switch. The window motor is tested and works, and I tested the pins and I am not getting 12 volts. I swapped the master switch with a spare, and it did not change.

I am not getting power to the black/pink (#3) wire like the passenger side. I may have shorted the wiring when I took the regulator out, as you have to dismantle the switch connector to removed the window motor. I did have the negative battery cable unplugged, but I had to move the car because of street sweeping, and I forgot to tape the loose connections. They may have touched when I moved the car.

Feeling a bit frustrated, hoping someone could help narrow this down. Thanks for your help.

I have the same issue with the same window... But pass front was working.... was... now it's has stopped also. There share same fuse, but its fine. I think I mouse visited? have not had time to tear into it yet, but will when I do the 4 speed manual swap.

When the front windows work and the rears are intermittent I find the trouble is usually with the "safety" or rear passenger lock out button.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

It's common for the wire(s) to break at the pillar-door interface.

A wire continuity check will confirm that issue.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

+1 The wiring used throughout the Mercedes harness has large strands, and a low strand count. This makes it prone to breakage where it flexes at the hinge pillars. I like to replace damaged wires with high strand count silicone insulated wire. This stuff is used as "ignition wire" for R/C models and is sold in hobby shops. Or you can buy online:

2Pcs 18AWG Tinned Copper Soft Silicone Cable Wire Heatproof for RC Lipo Battery

Thanks for the link. Looks like some good stuff to use for some other places where the binding and flexing causes problems.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

My Window Fueses looked good but when I pulled them I found one Fuse had the tip either corroded or burned off.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Probably not a fuse because the L rear window shares a fuse with the R front window, so if that works it the fuse is probably OK. But, I have found fuse problems from the factory silver fuses. I measured 12 V on the switch supply lead, but it dropped <1 V when the switch was actuated, and a high-resistance fuse contact was the culprit. Replacing with a gold fuse fixed those diagonal windows. It might be such that the current load of the R front is slightly less so it works while the L rear doesn't.

Anyway, you can do most testing from the console switches with a multimeter and a schematic. You should measure <100 ohm across the motor leads if wiring and motor is good. The rears have funky wiring because of the "rear lock-out" button in the front. But first get them working from the console switches. I found broken wires in the jamb feed-thru of my 1985 driver's door, which is a common problem. I am lucky my driver's window hasn't broken again since I must lower it 3 times on the way to work going thru security checks.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans