If anyone remembers my dithering about trying to use 4 used power window switches to replace my long since destroyed power seat switch, and my concluding that it wouldn't work.... well I was wrong.

I tried it with some bone-yard BMW E-30 switches, as there's a lot of those to pick from these days. I'm sure the MB window switches would work too and then you wouldn't have a hybrid. The BMW switches have a similar feature of the Saab switches that I had tried to dissect: some of the pairs of contacts that beeped the continuity tester when closed, also beeped in the neutral position. This threw me because I'm thinking that I didn't want power flowing to the motors when the switch was off. But then, I'm thinking, this would impair window function so I must be missing something.

Then I noticed that the pairs that were hot when neutral were only hot on one side of the switch -- up or down. It dawned on me that I could put the ground side of the circuit on those two pairs, one ground on up and reversed on down, since it would disconnect in the reverse position.

It was quite a puzzle to work out but oh, baby, it was satisfying when it worked and it works like a charm. Here's what it looks like:



And just for comparison, here's the passenger door w/ stock switch.



Like I said before, I like this car a lot but the seat switches strike me as a bit of stretch, a little too much cute and not enough solid function. With the window switches, if one switch goes bad I can replace it for next to nothing. The stock switch seems prone to losing one or two functions just from broken plastic. And my passenger seat will work in two of the functions one way only. Great, the seat keeps getting further and further out of position.

The whole thing cost me less than $20 but lordy, it took awhile -- 8 hours plus. (?!?) Just fashioning a way to hold the switches firmly to the door took a bit of doing. I was able to use the stock plastic trim and it is some sturdy plastic. Took quite a bit of abuse in the process -- one side is only about an eighth inch wide -- and it never broke.

If anyone out there is as crazy as I am in this dept and wants to try this, let me know and I'll go into more detail.

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1986 300SDL, 362K
1984 300D, 138K

That's very interesting, you might consider going into street rodding . I'm sure others will wonder why anyone would go to all that time and effort, but the feeling of conquering the challenge is the real payoff IMO.
BTW, did you try cleaning the switch on the passenger side? The symptoms suggest that this should get all functions going, for about an hours time.

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1986 560SL
2002 Toyota Camry
1993 Lexus

Yeah, it was a lot of time and effort but power seats are a bit of a pain to me. Manual seats are lighter and more reliable. I like to put my seat back all the way back and take a brief nap during lunch or break and w/ power seats, there's always the danger you won't be able to get it back up if the switch acts up.

I am going to try to clean the other switch. I have an after market remote unlocking device I installed on my BMW. The E-30 has an electric locking system but no factory remote. After about 6 months each remote began acting up -- I'd have to push the different buttons (3 total, never did get what the third one was for) to jump start it to life to get the function I wanted to work to actually work. And then they started to not work period.

One day, I accidentally spilled diesel on one of them and it's worked like a charm since! Who woulda thought...

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1986 300SDL, 362K
1984 300D, 138K

Interesting solution. MB has been using those seat switch's for years and they worked so well everyone copied them.

Usually they get dirt in them and will no longer work well. I pulled my drivers side one apart and cleaned it out real good, works like new. The pass one will not bring the seat forward I need to clean that one out as well.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I had decided my driver's seat switch had had it, oh, well, it is 20 years old. I had reason to remove the door trim (replace door check) and, while the switch was accessible, I played around with it a little. I finally just squirted it full of WD-40 and worked each switch around for a few seconds, then sprayed it again and shook out the liquid. A lot of dirty WD-40 dripped out onto a white cloth, and the switches worked perfectly when reinstalled. Not only did they all work again, but they were much easier to operate, and I no longer had to force them or make several tries to get some of the functions to work.
You might try this before you condemn your switches, and maybe before you break them by forcing them if they are dirty.

The original switch does have the benefit of being really clear about what function you're accessing. On my jury-rigged deal, I used the forward switch for moving the entire seat fore and aft, and the back switch for the seat back, with the two in the middle doing the tilt functions for the entire seat.

This 126 had been rode hard and put away wet when I came across it. I probably should have shopped around a bit more, but the body was almost perfect and the engine and tranny seemed fairly good and $1400 was in my range. Picture at:

http://www.peachparts.com/shopforum/tech-help/34132-w-126-roll-call-post1068638.html#post1068638

AND, I was hot to get a diesel. Err in haste, repent at leasure. The interior was beat up. The drivers's seat had a few broken springs and sagged badly. Fixed that.

But, I do like the rig. Both seat switches were badly broken. The driver's switch would move it fore and aft and that's it. Most of the parts were broken. Ditto for passenger side. The boneyards had nothing to offer. I got an e-bay switch for the passenger side and after it started acting up after a brief period of function, I was feeling a bit snake bit about buying new switches. A dealer parts counter guy told me they were $160 apiece plus $40 each for two adapter kits.

I see here at MS they would be about $170 each side for switch and kit. Hate to be a cheapskate, but... I get a kick out of salvaging boneyard parts and making them work. After I got into it, it became a challenge not to be beaten by it after I ran into the dead ends on figuring out how the switches work. They say doing puzzles helps keep your mind from aging as fast and unlike the rest of you guys, I ain't gettin' no younger.

Oh well, I've got a one of a kind seat switch. Bet that'll pull the ladies, eh?

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1986 300SDL, 362K
1984 300D, 138K

I think you guys are definitely right. I already bought a mostly intact passenger switch, maybe if I soak it in diesel for awhile (see post #3) it'll work fine. Don't know if I want to repeat the labor intensive task again, specially if I don't really need to.

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1986 300SDL, 362K
1984 300D, 138K

Actually I have a bucket full of about 6 of these seat switch's all apart. I got my drivers side to work fine but just pulling it apart and cleaning all the contacts. I need to do my passanger's side soon.

Just keep swaping around internal parts until you put together a good switch.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200