Where do I start
 

My next conquest (set of problems) on my '84 300sd is my front windows. Specifically, they have ceased to roll down. I can hear a vague ticking (when pressing the switch) only from the driver's door while the passenger side is silent. The fuses are not burnt out. What do I check first? Is it usually a result of a failed motor or regulator?

As always, all input is greatly appreciated.

Take the door panel off and observe the window regulator action, or not, while you operate the switch. There may be some broken bits inside. The junkyard may be a source of cheap parts or use Fastlane for new parts.

before buying anything take your vom meter and see if the motor is getting any voltage. if it isn't then it's up the line. check the switch. i've not done it but a few posts have indicated that some switches will come apart and you can clean them.

but the big thing is if no power to motor then work with the switch be sure voltage is coming into the switch and leaving the switch first.

good luck

Since it is BOTH front windows, it is not likely that both window regulators failed at the same time. Try to find something common between them such as a power feed or fuse.

If it weren't for the fact that both of them failed the first thing I would check is the switches. It is common for dirt and particles to work their way into these switches and make them fail. The good news about the switches is that you can carefully pry them out, disconnect them and pry them apart for cleaning.

Good luck,

much appreciated
 

You're right. unfortunately, I didn't see the correlation between both windows failing at the same time.

thanks again.

Make sure the window relay is working -- if not, all the windows will be dead. If the rears work, it's not likely to be switches either (if the front switch is bad, neither window will work).

Peter

Test Wires
 

I would open the door and hook up a battery direct to the 2 wires that go into the door and feed the motor...If you have the doorpanel off you will see a 2 wire connection. The motor will run by hooking up a pos wire to either wire and hooking neg wire to the other wire. Be carefull if you are removing the door panel from a 126-300SD because it doesn't pop loose like a 123 chassis but the 126 requires to be raised straight up because the connections are L shaped and not a male/female like the 123.......Jim

My experience with my '83 126 body is that water leaks down the shaft of the electric motors for the front windows which eventually locks up the motors. The culprit seems to be water leaking past the end play adjustment screw for the armature of the motor (it points upward in the installed position). On the last two motors I have replaced I have caulked this adjustment screw as a precaution but can't report whether has helped. The "vague ticking" you hear is the locked armature receiving power. If the windows are used frequently they will continue to work indefinitely but if you don't use them for a period of time (like during the winter months) they will cease functioning. I have disassembled these locked motors and freed them up without problem but the armature shaft is invariably too corroded and pitted for my tastes to permit a reliable grease and moisture seal. As for the passenger side, if it's not "ticking" it may still be the motor but is probably the fuse or switch.