Seat's back rest came forward: car undrivable

Check the handle on the side (the one that allows for one-touch folding to access the rear seat). It may not be fully depressed, which would cause a similar issue.

 

Ah, that sounds like perhaps a failed cable then. I think you'll have to open up the seat to find out.

 

The seat control ECU (located under the seat) may be on the fritz, or it could be just a bad contact, or it could be a bad potentiometer.

Remove the seat (easy - only four bolts but be careful because it's HEAVY) and before you take it out unplug the connector from the ECU (also easy - you'll see it immediately). Once the seat is out check all contacts as well as double-check the operation of all buttons on the side.

Removing the seat back (a few simple screws) will give you access to the potentiometer(s) that regulate(s) the motion of all seat moving parts. Do a search in this forum and you'll see that information about the seat potentiometer has been covered in the past.

Set aside an afternoon, get ready to learn about parts in your car that you never know even existed and have a good time doing it.

 

Weird. I forgot it had a seat ECU, asgor is probably right in that it could be failing. Good luck!

 

Each seat has its own ECU


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Sorry. Misread the question. Yes. One part of the ECU can fail. In my case it was the recline motion that failed but I simply found the circuits and fitted an external relay.


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Hi,

Removing it is easy otherwise, BUT the seats are VERY heavy. Definitely a two person job.
I had a thread in here about the ECU's some years ago, my driver's seat is still behaving oddly, in my case it looks like the problem is only the driver's seat position potentiometer.

For debugging you can swap the ECU's (they are all the same) and measure that all microswitches open and close the circuits as expected. I hate it that the ECU's are so undocumented, they are made in France IIRC by a company called "Actia" and contain mostly basic relays and capacitors and half a dozen semiconductors.

On mine when it decided to "fold forward" (tilt the driver's seatback as far forward as it goes) and not tilt back, what helped was to move the seat back and forward until a position was found where the seat back adjustment works both ways and then move the seat forward/back to the right position.

I thought for sure it was the switch or the ECU, but you can swap them from the passenger side to debug,a nd in my case only the position potentiometer seems be the culprit. It's a pain to replace so I left it as it is, I can live with it as I know now how to get everything in the right position and we use the passenger seat for getting in and out the rear seat.

Cheers!

 

Hi,

You're welcome. With "the handle" you mean the switch to operate the seat tilting? It did the same on mine, it would say "click" but would not tilt backwards (only forwards). On mine swapping the ECU or the switch from the passenger side did not help at all.

Can you get the seat to move forward or backward horizontally?

On mine this affected only the tilting of the seatback. Once the seat was in the "right" position horizontally it would tilt back and forward normally. So then I could adjust the seatback to the desired position and then move the seat horizontally where I want it to be. Then I could again no longer get the seatback to tilt backwards, the ECU would produce a "click" when the switch was operated but the seat would only move back and forwards, but not tilt backwards. Weird, huh?

I thought this might have been due to faulty (intermittent) wiring, but I was wrong, it appears to be only the horizontal POT for the driver's seat.
The quest continues.

Cheers!

 

Hi,

Looking forward to hearing what may cure your problem or if you can find a way to work around the problem, like I did. Sorry if I sound like a teacher sometimes, I'm not, and English is my fourth language, so I just try to explain a lot (see me waving my hands) to avoid misunderstandings. And I don't even speak Italian or French, so I guess my hand waving skills are not that good either.

 

Hi,

Sorry I have no idea about that small gear, I haven't seen one before. Then again, maybe it could be from the potentiometer and that would explain why it does not work normally anymore.

When I rebuilt the interior on mine, or lets say, I took it completely apart and cleaned and treated all the leather and then put it all back, I learned to hate the amount of ABS plastic in these cars. On top the interior is fantastic, I love it, so much leather and all, BUT underneath that dash is the AC unit and all the flaps and gears etc are made of ABS plastic as the unit itself too, and in time it crumbles to small pieces I was able to put it all back together (and there are special glues for different kinds of ABS, make sure you get the right one) and I disabled the "self-destruction" mechanism which is the two servos for closing the fresh air intake if you press the button for that function by pulling those cables. The thing is that every time the AC unit is powered up, it tries to close the flaps for the air recirculation, and if the foam is gone, it will push the flaps further and further, bit by bit and then they become disengaged, jammed and the rods are free to muve as much as they can.

A typical symptom of this problem is that the two servos remain on when the AC unit is on. If the flaps are closed and the servos meet enough resistance, the AC ECU switches the servos off. If the flaps are loose inside the AC unit, the servos keep on rolling and make this quiet "rrrrrr" sound all day long.

Sorry for this much AC talk, In hope you get your seat sorted out., the answer is that I don't unfortunately know, that gear may be from one of the seat motors or potentiometer, you will probably have to take it out of the car anyways and take it apart to find out where it may belong.

I was able to operate the seat out of the car by figuring out which wires have constant power and ground and using a 12V battery.
I think your car is also 1995 or earlier, mine is from 1995 and sold new in Japan.

Cheers!