removing power seats w/o power...how? - PeachParts Mercedes-Benz Forum

locry · #1 10-08-2009, 08:25 AM

i need to remove the seats... problem is, the car has no power at the moment. is there a way to manually move the seats without power? if not... is there a way to bypass the seat switches?

i need to move the seats so i can access the bolts holding the seats down.

samdon · #2 10-08-2009, 10:53 AM

Under the carpet at the hump for the front bolts there is a black, plastic sleeve containg four pairs of wires. They lead from the switch to a plug on the bottom of your seat. If you cannot get to the plug with the seat in its current position' you can strip back the black sleeve to reveal the 4 pairs. Each pair is individually wrapped so be sure not to remove the individual wrappings or you'll have a hell of a time matching them back up. If you can get to the plug; pop off the cap and pull out the wires...making note of their position, of course. The pins are soldered to the wires and make a nice chunk to apply power to. There are two more much smaller plugs that control the "key off, door open, seat on" feature. Leave them be until you get the bolts out then unplug them. Note: the power seats are heavy and awkward to hold on to.

The blue/purple pair moves the seat forward and backwards. You will also need to tilt the rear all the way up to get to the rear bolts which will still be a pain but ultimately possible. The orange/gray pair will do this for you.

You can use a 12v battery from a power tool if you have one. This will make the whole process at least one magnitude more pleasant. Reverse the polarity to perform the alternate movements.

The wire colors are from memory so if I botched a pair or two you can't hurt anything. You'll figure out which pair does what quickly enough. Keep your hand out from under the seat at all times. These MB power seat mechanisms are insanely strong. Severing a finger wouldn't even slow the motor down. Taking off a hand may cause it to breifly strain at best.

Good luck.

Sam

locry · #3 10-08-2009, 07:07 PM

wow!!! excellent tip my friend! many thanks!

though i don't know how you found out a finger in the way won't even slow the mechanism a bit.

haha

tinypanzer · #4 10-09-2009, 10:26 PM

Drill batteries are great, just use a 14v. I think 18v would border on risky for the motor, though probably not for very intermittent use.

Be extra careful, a drill battery is more than enough to trigger an airbag or seatbelt tensioner.

locry · #5 10-09-2009, 10:51 PM

thanks for the tips guys! i think i have an extra car battery lying around somewhere... my power tools are only 7.2v i think. sure beats having to lug around a car battery

Billybob · #6 10-09-2009, 11:32 PM

The easiest and quickest thing you can do is get a 12 V battery and apply power to the vehicles original battery connections, then move the seat with the door open. If you have access to a computer UPS they all use small 12 V gel cell batteries that are great for this, also Home Depot sells replacments for about $15 each. Theses gell cells are about 4" X 4" X 3" and weigh a pound or two. Eight regular D cell batteries can be taped together in a 4 x 2 configuration with a short jumper connecting the stacks at one end to create a 12 V pack also.

This is from an earlier post to a different thread with the same question!

"Under the driver's seat is the memory module, at its front top edge it has connections for the seat switch (a 14 or 16 pole rectangular connector shell), the power connections (a 4 pole square connector shell), and a second square connector(this has the head rest control and something else I don't recall at the moment, in a four pole square connector shell), at the rear of the module are four square four pole connectors, one for each of the seat base motors and one for the seat back motor.

Each of these motor connectors has four conductors two are power to the motor and two are position info from the position potentiometer attached to the motor shaft. I don't have one in front of me at the moment so I'm not certain but I seem to recall that there are two different gage wires used for the two functions, the heavier gage for the motor power and the lighter gage for the position signal. There may actually be different size electrical contacts in the connector shell, I just can't be sure at this moment. One can easily look at the wiring coming from the electric motor and note the color code then open the four pole connector shell and note the position of those wires.

It is not the easiest but I have on numerous occasions; usually when a switch, memory module, or wiring has failed, reached from below and behind the seat unplugged these individual motor connections and used jumper wires and a 12 volt source to move the seat base enough to access the 4 bolts securing the seat base to the chassis. As a result I've also constructed an abbreviated wiring loom with a seat switches , power, and ground connections that can be used by unplugging the vehicle's seat wiring harness at the front of the memory module and plugging my setup into the module's connections then attach power and ground sources. I can then hopefully move the seat independent of the vehicle's system; this is also an easy way to begin the diagnosis of seat switch and seat switch wiring issue possibilities. If the seat still does not function properly it’s likely a memory module, motor or cable issue inherent to the seat or its' base itself. This setup also works great if you’re ever retrieving seats in a bone yard. I've used it to test some extra seat switches for functionality also.

Early 126 chassis vehicles without seat memory function are wired directly from power/ground, through the door mounted seat switch to the seat motors. In this case the connection under the seat can be unplugged and power and ground applied to the particular pair of wires and a functional motor can be operated. Wiring for the motors is like colored wire pairs i.e. purple/purple-white striped and located in parrallel adjacent pairs 1/2, 3/4 etc. in the connector shell.

124 chassis seats have a couple different generations ending with the last generation having the integrated convenience module and integrated micro switch controls, but the first generation is similar to 126 Gen II."

locry · #7 10-10-2009, 04:52 AM

this is getting better and better!!! thanks bro!!! that independent module thing sounds like a plan!!!

will try to get that "extension" plug going.

best power seat tip ever!

all the tips are great btw...

locry · #8 11-02-2009, 10:10 PM

this is the plug... carpet is still damp and muddy

locry · #9 11-12-2009, 09:56 PM

quick update: managed to apply power directly to the motor. i stripped all the wires that i could get my hands on but ended up moving the seat in all directions except forward and back (go figure)...

i eventually spotted a blue/purple combo coming out of the forward most motor... as seen through the front...but was quite inaccessible. i eventually traced the wires to a junction box in the middle of the seat where all the motor connectors connect to... found the one with the blue/purple combo... DONE!!! woohoo (good call SAMDON)

the junction box is easier to access with the seat at its highest... good thing the first motor from the rear is the one that raises the seat...

will try to take pix this week

samdon · #10 11-13-2009, 09:10 AM

Good work, locry. I can't imagine tearing into a S-Class the way you are. You'll be an expert before it's over.

About the severing of digits. I didn't lose one, thankfully. Once I got the two front bolts out, I used an old broom handle to pry the seat up just a little bit to make playing with the wire combinations a bit easier. A few mm makes a difference in this operation, no? Well, somehow I put the broom handle between two parts that wanted to get up close and personal. The mechanism severed that 1 inch piece of hickory...no jagged break...just a clean slice. From the sound it made; you could tell there were some very powerful forces involved.