Window Motor vs Regulator?
 

How can I test to see which one is causing my windows to no longer go up or down?

I am going to the junkyard on sunday and I plan to grabbing some rear ones from a 300E...

Thanks

The way I test it is...just move the switch into either, or both, the up and down positions. If you can hear the motor humming when you move the switch, the regulator is probably the problem. If you can't hear the motor or it makse no noise at all the motor possible bad. Simple, does'nt work 100% of the time, but it's accurate enough. Or, before you go to the junk yard take the door apart and test the motors. using the same technique but visually verify the motor gear is actually turning.

At the wrecking yard when you remove the door panel, you will see a wire junction/connector for the motor and harness. Unscrew, remove the harness end, and apply 12v from a porta battery. The motor should go in one direction or the other depending on which leads you touch. Look for broken teeth on the regulator and observe the operation if it binds.

Rear window regulators on the w124 are very fragile.

They use a cable drive and the plastic piece the window attaches to, and is riding on the vertical track, is often broken. check to ensure the plastic is still clipped onto the vertical track.

The same vertical tack can easily be tweaked, and that will also cause the window to not operate properly.

There is a clip at the top of the assembly that requires the window to be down slightly to release, of you can bend the donor door inside panel to get it out.

Jim

Note: those Bosch motors often respond to just pulling out and and lubing the worm gear.

I don't hear the motor at all when I press the buttons. Thanks for that battery test. I will take one with me when I go.

I'll grab both because at some point in the future I am sure I will use the regulator. For whatever they charge (like $5) its worth just to have it in my "Parts Box".

The 300E rear window motor + regulator's are the same for the 300TE, correct? Just double checking.

I checked the numbers from one parts source and they are the same. I have yet to remove a panel on the TE to verify. The rear door sheetmetal is different, the TE is either longer in the rear qtr window or just squared off on top. I guess the triangle didn't look right to the designer...

One other thing to check on your own car, the leads can work loose at the motor. It worked fine after re-soldering it.

Sometimes mosture can cause electircal resistance to build up on the electrical leads at the motor.. If the leads screw into the motor then unscrew them, scrape them clean and reattach.

If there is a puug then unplug them and clean the contacts in the plug with some conact cleaner you can get at Radio Shack.

Just a little bit of resistance can stop the current from getting through.

Save a little time by powering up your motor directly. Remove the door panel, power the two screw terminals. Forward and reverse polarity will run it up and down, if it's from a jumper box and nobody's pressing the switches, you'll be fine.

There have been several owners of 124s who have had wiring failure in the B-pillar/door interface and cause the window to stop. Also, try opening and closing the door with someone holding the button down, if it starts to work it's your wiring.

A search on the diesel forum will show a DIY and pictorial, might be in the DIY forum by now.

I have a broken regulator cable on my RR door, and was wondering about the "updated" new ones that someone mentioned they had bought on ebay.

How can I know that the one I am purchasing is the updated one? I don't want to go through the trouble of replacing it again in the future.

PS. Didn't want to start a whole new thread.

Model and year will help to get an accurate answer.

Sorry mate
94 W124 E320 sedan.
RR door. I also have a 90 300E. Izzat going to be the same regulator?