Hello,

Car is '86 300E W124 176k miles. This morning I have lost power to all 4 windows and seats. It all worked yesterday -- at least all that I used. Where do I start? It really seems like a wiring harness or main hot or main ground has failed somewhere -- hoping someone knows where to look!

Fuses are all OK.

Does not work: in any key position
Seats
Steering Wheel
Windows
Added on 4/1:
Wipers and Wiper Wash
High Beams
Rear Defrost

Does work: with door open:
Seats

Does work: normally:
Radio
Antenna
Climate control
Cigar Lighter
All switch illumination (even to the window switches)
Headliner lights
Glovebox light

Thanks!

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award

I recently lost all power to the power seats on my '92 300e and the problem turned out to be the power seat relay located at the rear of the fuse box. This model has separate relays for the windows and seat and they can be interchanged for testing.

Earlier W124's use a different relay set-up and maybe a single relay controls both the power windows and seats - I'm just guessing but it is something to check.

Does work: with door open:
Seats


This may be a sign that there is a short in your wire between the door jam. If your fuses are O.K., then I agree with Mr. John Plut, your relay is burned. Check it under the seat. The relay is EXPENSIVE.

I know you checked your fuses, but try actually changing them. One time I had some electrical problems. I checked the fuse and thought they were o.k. I was going crazy looking for the short. One day my dad's friend changed the fuse while I was under the dash....all my problems were solved.

The fuse is about 5-10cents each. If they are still good, then just use them as an emergency replacement.

__________________
JR
1986 Gold 300E 4Dr automatic

has anyone been in the drivers floorboard area? have seen
two veh where the conv relay connector had worked loose.

it is located under the foot rest on the left side of the
driver footwell.

the x30 connector is a large, multipin connector that provides
ground,and power to circuits needing key on, key off, ect.

__________________
fabulous!

Thanks All!

At lunch I wiggled the wires around the fuse box and it worked for awhile and stopped again on the way home. As it began to rain, I noticed the wipers, high beams, and rear defrost were also not working! In the driveway, I got the systems to work intermittently with a firm slap to the top of the fuse panel. And by the by, I did a wholesale replacement of fuses less than 1 year ago.

I took the fuse box out last night certain that I would find a nasty mess of corroded and broken wires, but it all looked perfect and clean and dry. I also pushed and wiggled all of the relays while I was in there. I put it all back together and all is well so far. I did notice one of the screws on the relay panel cover was lose -- perhaps this was allowing the relays to work lose?? Don't know for sure but will repost if problem comes back.

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award

I'm now getting exactly the same issue with my 500E.. wipers don't work at all, and windows/seats etc only work with the door open.

Anyone know what the relay looks like as it may be in a different place on the 500.

Thanks,

Bri

__________________
Brian Drought
1999 Lotus Elise
1991 Mercedes 500E
http://www.briandrought.com/cars/

[QUOTE]Originally posted by d2bernhard
[B]Thanks All!

"I took the fuse box out last night certain that I would find a nasty mess of corroded and broken wires, but it all looked perfect and clean and dry."


David, did you remove the part of the fuse box that holds all the fuses, exposing the inside of the box with connecting wires to the underside of the fuse holders?

I need to add a wire to the hot side of fuse #3 and I would like to know if it is a difficult task to refit the fuse holder panel to reassemble the fuse box.

Please let me know,

Thanks,
Acky

I unscrewed the box and lifted it up. No, that part was not difficult.

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award

It's the fuse guys !

There's a fuse, can't remember which one, but it's a blue fuse and it's marked as doing the 'Comfort Circuitry' or something like that on your fuse information sheet.

Replace it ! Mine had a high resistance, enough that the relay had no power intermittently and would kill seats/windows/wiper/headlamp flashers etc. Replaced the fuse and problem solved.

These fuses can go bad even when they look fine.

Also, clean the contacts on the copper tab holding the fuses.

Bri

__________________
Brian Drought
1999 Lotus Elise
1991 Mercedes 500E
http://www.briandrought.com/cars/

bdrought you were right. It was a fuse, though mine was red. Comfort Circuitry. I must have jostled it around enough the time I took the panel out to reset it for awhile -- since April this year. This failure did surprise me as I replaced them all last year. Fuse looked perfect at face value but was rather fried up on the cap.

Attached Thumbnails

 

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award

David,
I don't think you are out of the woods yet. There are 3 main causes for fuse failure in these cars. They expand and contract with on and off current causing to break like a beer can. Putting in a new fuse solves the problem. A dead short will pop a fuse, and the short must be corrected. That picture leads me to believe you have the makings of the 3rd way these fuses fail. It looks like that circuit is constantly drawing excess current which is putting that fuse on the ragged edge. I suspect you have a relay that is tired and causing high resistance. I don't have my electrical books here now so I can't offer advice on what component it might be.

Peter

__________________
Auto Zentral Ltd.

Thank you Peter, if you do find out what components I need to check, I'd love to hear back from you.

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award

Hi

I see that you are using the aluminium strip fuse. I changed all of mine to the brass/copper type and all my electrical faults went away. The aluminium ones seem to oxidise very fast and still look OK giving one that electrical mystery headache.

Oreo

Oreo,
Ihadn't given that a thought. I'll have to remember that.

Peter

__________________
Auto Zentral Ltd.

FYI still no problems to date after replacing this fuse.

__________________
David
1986 300E Anthracite + ECodes + MB Mileage Award