Electrical Oddity - Can you please confirm my thinking? - PeachParts Mercedes-Benz Forum

Adriel · #1 07-22-2015, 10:50 AM

Long story short, window jammed due to the deterioration of the felt, removed the regulator, had a 2x4 to operate the window, prior regulator motor quit when installing, and the switch doesn't work. In the process found a blown fuse, but made no difference. Checked the wiring and 1.8 Ohms on the green and 2.4 Ohms on the black. That is a little high but wouldn't keep the motor from operating, correct?

So then, I have tried several switches and none work. So time for a brand new, which most likely will be junk also?

Thank y'all in advance for the help!

dude99 · #2 07-22-2015, 10:54 AM

The switches are easy to disassemble and clean. I would suggest you open them up inside a plastic bag though as the first time you take one apart the innards are almost guaranteed to go flying across the room. Give the contacts inside a sanding with some very fine sand paper and reassemble.

Are you getting voltage to the switch?
Voltage to the motor?

Maxbumpo · #3 07-22-2015, 11:14 AM

I like using a pencil eraser rather than sand paper, just push the eraser against the contact and spin the pencil between your fingers. De-Ox-It is a great contact cleaner but a bit pricey.

Adriel - try measuring the resistance in the wires while opening/closing the door. The accordion boot in the door hinge area may be covering up some frayed wires, which will pass some current for your test but won't pass enough for the motor to work, and may also explain the blown fuse when two wires rub against each other.

Adriel · #4 07-22-2015, 11:26 AM

Thank y'all for replying so soon!

Didn't expect it but checked my mail gor grins, and I am grinning.

Quote:

Originally Posted by dude99

The switches are easy to disassemble and clean. I would suggest you open them up inside a plastic bag though as the first time you take one apart the innards are almost guaranteed to go flying across the room. Give the contacts inside a sanding with some very fine sand paper and reassemble.

Are you getting voltage to the switch?
Voltage to the motor?

I don't know, but after posting, crossed my mind... How do I test that I am getting voltage to the switch?

Quote:

Originally Posted by Maxbumpo

I like using a pencil eraser rather than sand paper, just push the eraser against the contact and spin the pencil between your fingers. De-Ox-It is a great contact cleaner but a bit pricey.

Adriel - try measuring the resistance in the wires while opening/closing the door. The accordion boot in the door hinge area may be covering up some frayed wires, which will pass some current for your test but won't pass enough for the motor to work, and may also explain the blown fuse when two wires rub against each other.

If I need De-Ox, bet one of my friends has some to spare a few drops.

Good idea! Will do after breakfast.

dude99 · #5 07-22-2015, 11:31 AM

Quote:

I like using a pencil eraser rather than sand paper

On cleaner contacts I agree, however I find on some that have a heavy carbon buildup an pencil eraser doesn't cut it.

Quote:

De-Ox-It is a great contact cleaner but a bit pricey

Its worth it, we got through a lot of it at work... A can should last your average individual a while anyways.

Quote:

I don't know, but after posting, crossed my mind... How do I test that I am getting voltage to the switch?

One of the wires coming into the connector that the switch plugs into should be hot with key on, I can't remember which color it was off hand.

Adriel · #6 07-22-2015, 11:39 AM

Quote:

Originally Posted by dude99

One of the wires coming into the connector that the switch plugs into should be hot with key on, I can't remember which color it was off hand.

Thank you for confirming my thinking!

Should be red according to D.I.N. I.I.R.C.. Black is switched.

Adriel · #7 07-22-2015, 12:17 PM

Okay, checked and have 12.1 volts at the red wire.

Got the wires to 0,1 Ohms. I find no damage to the wires, but something is odd, but for now, if it ain't broke...

Then connected the wires, tried a switch and nothing. So, jumped the connections and... It worked! Wahooooooooooooooooooooooooooo! So at least now can operate the window, which is nice for the dog as no A/C.

Again, thank y'all for the help!

dude99 · #8 07-22-2015, 12:44 PM

Pretty much confirms the switch is bad. Pull it apart and clean it and you should be good!

Adriel · #9 07-22-2015, 12:59 PM

Quote:

Originally Posted by dude99

Pretty much confirms the switch is bad. Pull it apart and clean it and you should be good!

Nope, my brain has been too warn out... Circuits need flow.

However, up was down and down up!

Apparently prior to about the early 1980s, the motors were wired different. This unit is from the '79. SO just witched the motors wire and das ist alles!

Man this window is so nice with the grease and the repaired felt from the '79: can't wait to get on the highway and see how quiet it is. A tad stiff, but figure due to the thicker channel.