"FIXED--DIY Added" Seat Flex cable on 1994 E320 Stripped--Now What?
 

My power seat has malfunctioned with the seat bottom at maximum vertical height. When you try to lower or tilt the seat bottom, only the left side of the seat adjusts--the right side stays at max height. This causes the seat to twist markedly to the left--not good. If I leave it at max height, the seat is straight but my head touches the sunroof.

After researching the problem in the site archives, I concluded that one of the seat flex cables is broken or has popped out its drive socket. I removed the seat and located the offending cable. I removed the retaining clip from the motor end and twirled the cable and it freewheeled. So I then tried to seat the cable deeper in the square drive socket to see if it would engage the seat adjuster, but no dice--still freewheeled. Tried to remove the cable to look at the square end that goes into the seat adjuster mechanism to see if it was perhaps rounded, but it won't come out. I removed the retaining clip on the seat adjuster end, and the black outer sheath slipped right off the flex cable, but the steel flex cable is still firmly stuck in the adjuster drive socket.

I assume this means something inside the "adjuster housing" is stripped/broken and is jamming the cable removal. Anybody know if this "adjuster housing" is a repairable item and if it is something that a shade tree mechanic can do? If I have to do a junkyard search, what is the correct name for the part that the flex cable fits into?

Thanks in advance for any info/suggestions.

If my memory serves me correctly, the left and right side of the raise/lower mechanism are connected via a torque tube. On the end of the tube there are raise/lower arms. If it were my car, I would look for broken arm or torque tube parts......

Hope this is helpful. Let us know what you find.

J. M. van Swaay

I am in the process of fixing the same problem where only one side of the rear of the seat will move. In my case the square drive cable appears to be a little too short and when the square drive is pushed all the way into the motor, it doesn't engage the gear head actuator. I am thinking about removing the metal end on the cable casing and shortening it by about 3/16".

It is easy to disassemble the actuator and see how it works. The square drive cable fits into a worm gear and I assume that yours is somehow caught but I do not see how this would cause a failure of the seat because it should still drive the worm gear. Have you had any luck solving your problem? Perhaps is is stripped and has stopped 45degrees from where it should be and the friction is great enough to make removal difficult.

For the record, this actuator is a two stage gear reduction. The first stage is a worm gear and the second stage is a planetary gear.

Power Seat Cable Repair on W124--Part 1 Pictures Included
 

I have been remiss in not reporting the resolution of this problem. It turned out that my seat adjustment cable on my 1994 E320 was defective (square drive cable had a "rounded" end that would not properly engage the square drive socket). As a temporary fix, I devised the "Redneck Power Seat Adjustment" tool that may be of interest to some of you--picture attached. In response to my wife's desire for a more "technically pleasing" solution, I decided to perform surgery on the offending cable by adjusting the length as described in several posts on this site. I am including pictures of the process for modifying the cable--sort of a brief pictorial DIY. Since I can only post 5 attachments with this posting, the remaining pictures are in a Part 2 posting that follows. I am happy to report that it fixed my problem. Cheers, John Downey

Power Seat Cable Repair on W124--Part 2 Pictures Included
 

These are the remaining pictures on how to modify/repair the seat adjustment cable.

Excellent documentation!
This is exactly what I was thinking about doing to fix my seat. In my case the square cable was not rounded off but had just slipped back toward the motor enough so that it became disengaged. After carefully measuring the amount of engagement at the motor end (about .60"), I concluded that I could insert a .25" long spacer made from an old o-ring that had about a 5mm cross section diameter into the square drive socket at the motor end and thus provide the necessary cable length to properly engage the actuator. I did not disconnect the cable sheath at the motor end (looked like a lot of screws), I just removed the center drive cable, inserted the spacer, and pushed it into place by reinserting the drive cable.
Just finished reinstalling the seat and everything works as it should.

An interesting observation during this process was that the seats without the memory feature use a different cable because it doesn't have to pass through a feedback potentiometer. When I measured the minimum amount of engagement in the actuator (cable pushed all the way into the motor) the dimension was .20" longer than on the seats with memory feature. I wonder if this was a design error?? Have others had this problem on seats without the memory option or has the problem been documented on the passenger seat that doesn't have the memory feature?

Bump for some awesome instructions.

Submitted
 

to webmaster for DIY wikki.

This will be a great generic DIY for all MB with power seat drive cables. :D