W126 Memory seats
 

I searched but most threads seem to just dead end with no actual results. Both my memory seats do not work. Buttons are not stuck and one set I recently cleaned. So I am pretty sure that with at least one its not the switches being sticky.

So how do they work? The seats operate fine (well except the passenger side which burns up the control board if forward/back is used for more than a second). Anyway. I press the green followed by a number within 3 seconds. Then I wait, adjust the seat and press a button (or hold a button down, manual is not clear) but nothing happens with either.

Do they have independent computers to control the memory function. And if so, is it the big black box under each? One of which I have repaired a few times :). And while I am on the topic, what the heck is the bright yellow box under the driver side blocking the under-seat vent?

I believe you need to hold the green button in to program a memory position.

-Jason

As in press a number then the green button? I am pretty sure the manual said green first, then a number. I will read it again though.

I have the manual but need to fly out. I will read it later and post what it says,

You press and hold the green button, then tap a number button.

FWIW 1991 cars have a different memory unit for the seats. It's more digital and should be more accurate.

-Jason

+1 on hold green in and touch memory number. By the way it will also adjust the steering wheel to saved position.

Ok. I will try that. I was just pressing the green button then pressing a number after letting off the green. I was not holding both or pressing both at the same time. I even read the manual and it just said to press the green button followed by a number.

Qute from manual
 

storing seat/ head restraint/steering wheel position in memory:

press green button and within 3 seconds press the program button 1 or 2 for that position

So doing as above, as I have been doing, does not work for either. Holding the green button down while pressing a number does also not work. Also, as I read somewhere, holding the number down until the seat finishes moving does nothing.

So it looks like, oddly, BOTH of my memory seat functions are out. Yet the seats operate.

Strange. Once the memory is programmed you have to hold the button in to make the items move to the remembered position. If you release the button they stop.

-Jason

Ya. Thats what I understood and so I tried holding he number instead of just pressing it - like more cars. Still nothing.

So maybe programming is working, but recalling is not. Just odd since the seats work find otherwise. Maybe I will have to take the doors apart and check the wiring. I found so many cut wires when I was installing the sounds system. They were from the PO doing a hack job in the sound system in the first place. I found wire clear cut and nicked bad. Just odd that all the controls work though.

And I did check to make sure all the connections under the seats were plugged in. Guess I will add it to my list of "really simple projects that turned out to be complicated".

It's never good when a hack tries to "upgrade" a car which has a 2 piece radio set....

-J

I own a 1991 560SEC and had the memory function of both seats stop working after a voltage surge. Try unplugging the translucent white relay in the fuse box for 5 minutes or so and plug it back in and try to reprogram. This worked for me. Mark

I will try. But they did not work before or after I pulled the battery.

My seats behaved like yours after I installed a rebuilt alternator. When I started the car for the first time there was a loud pop, huge electrical draw and burnt electrical smell. I checked to make sure I hadn't somehow botched the installation but everything was installed correctly. So I started the car again and everything except the seat memory worked fine including the alternator. I could adjust the seats by moving the switches but could not set the memory. I checked the fuse, etc. and found nothing wrong. I began looking on ebay for seat modules but based on price I purchased a used seat relay and installed it and the memory functions worked. Out of curiosity I reinstalled the old seat relay and the memory functions worked. Unfortunately, I did not try the memory functions immediately before replacing the relay with the good used unit. The seat relay for this vehicle appears to be much more than a relay with IC's, smd's, etc. and I assume it has some protective function for the control units similar to the OVP. The part number is 0015427819, it lists for about $56 and it looks like the attached. Mark