1970 W114 250C Power Window Electrical Diagram

[mercifiknow]

Anyone have a wiring diagram of the power window as it relates to the rest of the system? I have the overall diagram from the Mercedes Shop Chassis Manual but not seeing anything related to the windows. My driver side motor works fine (I pulled it and tested it and it runs). My opposite rear passenger doesn't work as well and my fuses (located on the engine bay firewall passenger side) look ok but I'm going to the parts store to get knew fuses just in case. Otherwise this thing is going into the shop to get it fixed. Getting REALLY tired of this window problem!!!!

Thanks Everyone!

[Frank Reiner]

Originally Posted by mercifiknow

Anyone have a wiring diagram of the power window as it relates to the rest of the system? I have the overall diagram from the Mercedes Shop Chassis Manual but not seeing anything related to the windows. My driver side motor works fine (I pulled it and tested it and it runs). My opposite rear passenger doesn't work as well and my fuses (located on the engine bay firewall passenger side) look ok but I'm going to the parts store to get knew fuses just in case. Otherwise this thing is going into the shop to get it fixed. Getting REALLY tired of this window problem!!!!

Thanks Everyone!

Although you did not clearly state what the problem is, is it in fact that the LF & RR windows are inoperable?

If so, understand that power for the windows is supplied diagonally, both through the fuses and the relays. LF & RR are one diagonal pair, and RF & LR are a pair.

[mercifiknow]

Hey Frank!

Yes, it is the driver front/ passenger rear. Again, I've pulled out the motor and it is fine. So I have a broken wire somewhere, a fuse, or maybe a relay. I think my switches are good but not sure how to check the switch. As a disclaimer I am absolutely horrible when it comes to electrical work.

Thanks for the help!

[ejboyd5]

Don't over think the situation and create unnecessary work for yourself. Clean the fuse contacts and replace the fuses before you do anything else. LF and RR inoperability is a fairly strong clue as to what is wrong.

[mercifiknow]

Ok so today I checked the fuse contacts using a continuity light and found that the one set of contacts closest to the carbs/engine (Passngr under Hood_1 pic) did not give off a light. I cleaned (with some electrical component cleaner) the contacts and replaced the fuses and got no light still. I have a 25 Amp fuse in there so I think it is fine but again my disclaimer (Not a electrical person)...

What's next?

May thanks to all!

[kraakevik]

You'll probably have to mechanically disassemble and scrape off and buff all the screws, wiring eyelets, brass contact surfaces and fuse ends with emery cloth or some such.

The power-window fuses and those for other auxiliary equipment are located in snap-off-top fuse boxes on the passenger-side firewall under the hood. They tend to malfunction even when they look fine. Good luck



Tim
kraakevik@voyager.net

[Frank Reiner]

Originally Posted by Frank Reiner

Although you did not clearly state what the problem is, is it in fact that the LF & RR windows are inoperable?

If so, understand that power for the windows is supplied diagonally, both through the fuses and the relays. LF & RR are one diagonal pair, and RF & LR are a pair.

Originally Posted by mercifiknow

Hey Frank!

Yes, it is the driver front/ passenger rear. Again, I've pulled out the motor and it is fine. So I have a broken wire somewhere, a fuse, or maybe a relay. I think my switches are good but not sure how to check the switch. As a disclaimer I am absolutely horrible when it comes to electrical work.

Thanks for the help!

See the highlighted words "relay(s)" ? Start swapping relays. They are above the RF footwell cover panel.

[Idle]

What Frank said about swapping relays is a standard test in this situation. If the problem transfers to the two working windows then you have found your problem.

You can also have someone hit the window switch while you have your finger on the case of each relay. You can both hear and feel these pull if everything is quite.

And some of these relays cost around $270 each but if you have one of those Ebay might be a good source. If they are the cheaper relays, and one of them is bad, Pelican should have them and just replace them both and be done with it.

[mercifiknow]

I found the problem. Well, actually my friend did. When I bought the car, the windows worked. My plan is to restore the car completely like it came off the show room floor. Hopefully!

In my happiness in owning my new car and project, i noticed that the fuse block (where the fuses are housed for the windows) had a busted top cover. I ordered one from the MB Dealership and installed it. I noticed that it didn't look the same but I figured they discontinued it and would track down an original one later.

This is where the problem began and me not knowing it and trusting the dealership. I kept the old block in my tool box and was going to use it as a reference for purchase later. My friend came over and we discussed the issue. He asked if i still had the old one, i said i did and we immediately put it on. it freaking solved the problem. I was so mad. I spent all that time researching and dismantling things over an incorrect part. Anyways, lessons were learned and knowledge gained. Sorry it took so long to wrap up this thread but I thought there might be someone in my shoes later who might glean some wisdom from my labors!

Thanks to all who helped on this and the actual other thread concerning this problem.