My drivers seat will not move. I bought and replaced seat positioning switch (with memory) which did nothing. I would be satisfied if I could just move the seat to some upright position and use cushions.

Does anyone know how to remove the seat? I have looked extensively underneath and do not have a clue how to do this.

Any help or suggestions would be greatly appreciated!!

Bob

Was there any power at the switch ?

The seat needs to move all the way rearward...pry off rail covers and undo bolts to floor through the seat guide rails.
Move seat forward for access to rear rail bolts.
Tilt seat to the rear to access the power plug under the seat

Of course, this is all academic if the seat has no power.

There are two relays in the relay holder to power the seats and windows.
Do your windows roll up and down ?


I presume you have checked and cleaned all the fuses ? Some of the fuses are made of aluminium....these corrode and lose power.....buy the copper ones from MB.


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THANK YOU for your reply!!

I have not tested the switch.

What kind of power should I see there?
What poles do I need to cross with Voltmeter to get a reading.

Set is reared back so that I cannot access the rear bolts to remove seat.

Power windows do work. Power door locks do not.

When I got the car (1 month ago) I replaced all fuses in the fusebox in front of the driver seat in the rear of the engine compartment. Are there any other fuses I need to replace?

What relays need replaced? Can you give me the number on top of them? How do I test them?

...........................

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Cannot give you details of pins, but there must be at least one with 12 volts.

** I will test switch to find if 12 volts.

The auxillary relay/fuse box is back of the box under the windshield, lid has 4 screws.
There are two fuses in there at the back. These are for the anti theft warning system....ck them anyway. Some of them interact with the door switches.
**I have replaced these fuses also.

does the steering colomn adjustment work ?
Yes
Same power source.....Ck fuses 2 and 9.
**both of these were replaced but I will check again!

If this does not work the seat memory control may be bad. This is under the seat. I have changed two of these over the last few years.
**What is cost of the memory unit?

I will get back to you after I perform the above.
Thank You for your help!!
Bob

Here is what I found when I tested the wires coming to the drivers seat switch:

First of all there are 2 connectors:

1.Connector 020 545 98 28
On a vertical plane and has 3 wires connected to it:
White/Red
Brown (in center)
White/Brown

I was not sure which was negative or positive but I assumed the center was the ground (also on other switch wires below)
A). The White/Red was the topmost wire
1). Using the center as negative I got a maximum of 350 mV
2). Using the center as positive I got a maximum of -400mV
B). The White/Brown wire was below the center post
1). Using the center as negative I got a maximum of 5 Volts
2). Using the center as positive I got a maximum of -5 Volts

2. Connector 020 545 97 28
On a Horizontal plane and has 3 wires connected to it:
White/Green (closest to front of door)
Grey (in center)
White/Yellow (closest to rear of door)

Again, I was not sure which was negative or positive but I assumed the center was the ground.
A). White/Green wire
1). Using the center as negative I got a maximum 5 Volts
2). Using the center as positive I got a maximum of -5 Volts
B). White/Yellow wire
1). Using the center as negative I got a maximum of 5 Volts
2). Using the center as positive I got a maximum of -5 Volts

Checked fuses E, F, A in Fuse box all were ok
Checked fuses 2 & 9 in Fuse box both were ok

Again, thanks for all your help!!
Bob

Need to ck pin to body ground to find volts.

According to the schematic, the pin #3 on the 6 gang connector in the door switch(Brown.) is ground.

All the wires, except the BROWN, from the door switch go directly to the seat ECU.

The switch operating voltage may indeed be 5 volts, as the ECU is controlling the function of the seat with internal switching to drive the motors.

A GREEN wire and a WHITE wire supply 12v to the seat ECU..from fuses E and F.

It does sound like the seat ECU is bad.

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What is an ECU?

Is that the unit located under the drivers seat?

Any idea what the cost is?

Any idea how I can get to it without destroying the seat?

ECU = Electronic Control Unit....Seat brain, etc....

$50.00 to $150.00...who knows.

Cut a hand sized hole in the seat cushion and.........

No, really....With the front bolts removed from the track you might be able to lift the seat high enough to unplug the ECU/Memory unit. ....
You'll need to do it and see.


.

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"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

ECU = Electronic Control Unit....Seat brain, etc....

$50.00 to $150.00...who knows.
-------------I shall find out.

Cut a hand sized hole in the seat cushion and.........
-------------Don't think I haven't considered this

No, really....With the front bolts removed from the track you might be able to lift the seat high enough to unplug the ECU/Memory unit. ....
You'll need to do it and see.
-------------I will give it a try. Its back like a rocking chair so there may be enough clearence.

-------------Is there any way to test it to make sure or have we pretty much eliminated any other possibility?

Not really....unless you can check the power into the ECU and the switch input to it too.

If your sure your getting power into the ECU it is pretty conclusive the unit is fried.....after all, you have no idea of the history behind this car.

They do go bad, that I do know...saying your is , is just an educated guess.

If you can trace the GREEN 2.5mm and WHITE 2.5mm wires to the ECU you can verify power at the unit..12 vdc.

The wires terminate at a 4 gang plug on the ECU....The other two wire colors are...BROWN 2.5mm thick, to ground and White .75mm thick, to connector block near fuse box.

The only good thing is that there is only one 4 gang connector on the ECU. The rest are, six 5 gang and one 16 gang. All the 5 gang connectors go to the seat motors.



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I just checked with my local dealer the cost is $550 retail.
Any suggestions where I could get this at a lower price?

There's dozens of wrecking yards dealing with MB...Run a ck on Google or call a local wrecking yard and ask to put it on the hot line for you.
Some have hot lline some dont.

Here's one I always use ..talk with Brian.

I-35 Imports.
1-405-799-2886.

they are on the WWW too so ck for an 800 number.

Brian said he has to ck, but he thinks he has one there...$100.00 + shipping.

You might have the part # ready to identify the unit.

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can you hear or feel anything when you activate the switch. it could be that that the motor is turning but the square headed flex cable that runs from the motor to the movement gear is stripped, loose or pulled out and it just turns freely. listen for any sound or thump when you activate the seat switch, this means power is going to the motor. $25-$35 cable at the dealer.

__________________
1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification

Will try this and see.
I'll take $35 instead of $550 any day
Bob

1992 MB 300E 4Matic 99,999 Miles
1982 911SC Targa 163,000