My wife has a 1998 C230. The drivers seat works forward & backwards, but the seat back will not tip forwards or backwards. Before I start testing things I know nothing about, has anyone had (& fixed) this same problem?

Thankful for any info.....

I never heard of it on this car (yet...). I had a similar problem with the drivers headrest not working. In that case it was another case of failed solder joint on single-sided circuit board. But this time it was right at the motor for the headrest which is in the seat back. I am not sure of the location of the motor for the seat back, but could be in the set back also, otherwise it would be under the seat. The back trim panel of the seat is pretty easy to remove. There are two torx screws on the bottom. If you search for my head rest thread then I tell the size of the torx there. You would then put a volt meter on the motor connections or wire to it and see how far the voltage is getting.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

What about the same problem with the front windows?? Another relay perhaps?

Is it both driver and passenger windows?
or an issue in the center console.

What year is the car? and does your remote have the windows-down/up feature? and will the remote move the windows?

1998 C280. Remote doesn't have window controls. It's just the driver window. Other issues are the seats work intermitentantly (that's how I got onto this post) and driver side electric meter isn't working. This is a car I am looking at buying for my son. I am trying to see if these things can be fixed reasably cheap or if I should not buy. The owner says windows just randomly start/stop working. Thanks for any help.

I have a 98 C230 and the driver's seatback does not work anymore and is stuck in an uncomfortable position. Anyone else ever had this problem? Can it be the relay in the trunk?

Another set of power seats fixed thanks to You guys, thanks!

Great write up and great pics too. I removed front trunk panel, (3 large plastic screws), removed relay using two small screwdrivers on sides, carefully pried it apart using two screwdrivers, looked with magnifying glass and found 2 cracked solder points. Carefully resoldered those two spots, took all of 30 seconds and I don't solder much at all, plugged relay back in and it works like a charm.

Many thanks to all who posted!! Awesome fix!!

The information on this thread described the exact problem and solution to a problem I've been having with my C230 for years. Can't say how many times my wife and I have driven with the seats adjusted wrong while waiting for the adjustment controls to start working again over the past 5 or more years. My C230 had only one large black relay in the forward right corner of the trunk under the large black screw down cover. The relay lays on it side and connects directly into a connector on the wiring harness. The whole repair probably to 30 minutes. Here are the steps:

1. Remove trunk carpet.
2. Unscrew 3 large plastic screws in large black plastic cover panel that covers the entire forward trunk floor. I was able to unscrew with my fingers.
3. Remove the cover to reveal electrical components including the seat adjust relay.
4. Use a small screwdriver to release the plastic retention hooks while wiggling the relay out of the connector (pull toward front of car) to remove relay unit.
5. Use a small jewler's screw driver release the cover from the relay.
6. Examine the solder joints on the circuit board with a magnifying glass. Mine had the exact circular fracture on the large solder joint near the middle as show in a photo in this thread.
7. Use a soldering iron to reflow/apply more solder.
8. Reassemble.

Seat adjustment works great. I'm glad I declined my mechanic's proposal to replace the computer module a while back, a repair that would have cost over $1,000!

I found it...it is located further forward under the truck liner.
Almost at the back of the right seat, far further forward than the photos of the usual location depicted.
It is lying flat vs vertically.
I could see, with a powerful magnifier, that the solder was sheared horizontally right around pin.
Reheated a few pins to have the solder reflow and all is good in the world.

Took me 10 minutes to complete the job - taking out relay, soldering 4 post points and re-installing. Great feeling that I save $35.00.

Thank you for posting pictures - without them I would have been lost.

Hawk Wala

Another thread that saved a trip to the indy for diagnosis and repair. The relay cost $32 on eBay for the M-B branded Siemens part, although my indy said he could get it for me for a few bucks less and let me install it. Getting it delivered to the house was worth the extra day and dollars.

I noticed that some folks mentioned opening up the relay case to inspect and perhaps renew solder joints. I gave it a try with some thin pry blades, but couldn't get past the clips.