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Seat potentiometer location.

Discussion in '456/550/575' started by 456enthusiast, Nov 20, 2020.

  1. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy
    Hi there guys,

    456 M (2001 built), I'm trying to solve a problem related to the driver's seat tilt motion (the seat is reclined in the forward position and would not move from the darn place).

    Fuses are fine, the red micro switches on the seat sides seems to be working when I move the lever at the top.

    Next thing I guess is worth checking is the seat potentiometer and the tilt motion motor.

    I'd really appreciate if somebody a shed light on where they are located.

    Here's some pics of the seat. (maybe both potentiometer and tilt motion motor are in front of my very eyes and I'm just being blind like good ol Magoo :)

    Thanks a lot for reading.

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  3. Qavion

    Qavion F1 Rookie

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    Although the wiring diagrams indicate that the connector for the potentiometer is in the middle of the seat, the wires for the potentiometer are red, yellow and black. Could it be here....

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    These potentiometers are normally driven by a fluted drive rod. I see something like that below that white rectangle.
     
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  4. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy
    #3 456enthusiast, Nov 20, 2020
    Last edited: Nov 20, 2020
    Thanks so much, this is really helpful, couldn't find that diagram anywhere! Do you know if it's for the 456 or the 456M (or maybe it applies to both of 'em :)

    Also, if we wanted to try to apply 12V power to the tilt motion motor would we be looking at the 4M power supply or should we apply it on the motor where M6 connects (which I guess is the top one showing in this pic) ?

    Thanks again !
     

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  5. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
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    P.S. Also, shouldn't there be two potentiometer for each seat (one for tilting and one for seat track)? Cheers
     
  6. Qavion

    Qavion F1 Rookie

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    #5 Qavion, Nov 20, 2020
    Last edited: Nov 20, 2020
    After looking at all the diagrams, I have no clue how this seats works :oops: I thought the potentiometer was on the seat back recline, but looking at the parts manual at Eurospares....


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    ... motors 1A and 1B appear to drive #3 (x2). These components are for seat lifting. The potentiometer appears to be part of the lifting system.

    Motor "8" and gearbox "10" appear to control the (seat back) recline

    I have lots of diagrams, but you would need a training course on how to read them :confused:

    I created a diagram for the seat internal wiring:

    https://www.dropbox.com/t/9BKPa9Kdq3Trgjp7

    Here's the wiring diagram showing power and other wiring going to 4M (labelled "29F")

    https://www.dropbox.com/t/eUgR4Tq02TTmS7sr

    The seats use a combination of battery and ignition key power and a lot of logic inputs.
     
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  8. Qavion

    Qavion F1 Rookie

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    I wish Ricambi USA still had Ferrari part manuals online. They told you exactly how many parts were fitted.

    Does your car have a memory function which remembers all the settings? Tilt, fore-aft, height, etc?
     
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  9. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy
    Yes, it does have memory functions but they aren't working either.

    Ian, thanks for the diagrams though. Given how common this problem appears to be, it kind of sucks that it's not possible to move the seat back in some sort of mechanical way. I have read that it should be possible to apply 12V external power to tilt the seat back in place. From the diagram i gather that power should be applied on motor 8.
     
  10. Mirek

    Mirek Formula Junior
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    Oct 20, 2019
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    I have the EXACT same problem on my 2003 456M. The fuse was blowing that controlled the forward/aft movement and the dealer located a pinched wire, fixed it but my seat does not have the memory function or the automatic movement when pulling the level to get someone in back.

    After 3 trips to the dealer I am still living with it and appreciate the info you shared.
     
  11. franschman

    franschman Karting

    Dec 18, 2017
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    Bart Boosman
    I am also following with interest as my passenger seat went down but never up again. It's on the 'to do' list but somewhere down as the seats are out of the car and not yet due for getting back in.
     
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  13. Qavion

    Qavion F1 Rookie

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    Seems so.

    If there is a memory on all elements of seat movement, I don't know how it's done. I can't make any sense of the wiring diagram (it seems to be missing a few elements). How many wires go to each motor? If more than two, say 5, then I'd say there were potentiometers inside each motor.

    Surely the memory system can't be based on the time the motor relays are energised? It would soon go out of calibration.

    Were you going to repair or replace the seat potentiometer? There is a repair kit available on eBay (for the part that most commonly breaks).
     
  14. Qavion

    Qavion F1 Rookie

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    Looking at this pic of a 456M seat motor I found online, there is clearly more than just power wires going to the motor. Each motor must have circuits inside it (whether it be relays or other things). Unfortunately, it's still not clear from the diagrams whether you can apply power directly to the motor to make it run (and how that will affect seat memory calibration).

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    If you can get the seat to run by just applying power to the motors, I would make sure you drive the seat back to its original position.
     
  15. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy

    Worked on it yesterday

    Tried swapping the ECU unit from the non-functional seat over to the working seat & vice-versa. Both are fine. I know the switches are working (I had them tested) and I know that the tilt rotor does move (although only for a fraction of second) when I engage the tilt lever (hence the lever indeed triggers the electric signal). Fuses are fine, the red micro switches on the seat sides do work when I move the seat lever at the top.
    Also I’m pretty sure nothing is stuck in the rotor jamming it.

    I guess after all this troubleshooting I can only try to purchase a new potentiometer and see if that does te job. I will only need to double check how many potentiometers are located in the seat (on the on-line diagrams I can only see one, but I‘ve read (several times) that there should be two pots, one for the tilt motion and one for the seat track). I will send Eurospares a mail in the next few days, in the meantime it’ll be great if anyone could shed a pot light (now, that doesn’t sound right does it ? ;-)
     
  16. Qavion

    Qavion F1 Rookie

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    If you do buy a new potentiometer, don't throw out the old one. Here's the repair kit which should work in most cases:

    https://www.ebay.com/itm/Ferrari-355-seat-position-potentiometer-drive-repair-kit-/143665671697

    It's showing out of stock, but I would contact the seller, NilesH (I've tested and helped develop his product). The part works for both 456 and 355. Unfortunately, these systems usually require a Ferrari SD tool to recalibrate them.

    I'm not completely convinced that the potentiometer shown in the parts manual is connected to the lifting motors (#1). I think the parethesis may have been incorrectly placed. I guess you will only know once you start replacing the potentiometer (if it's on the seat tilt axis)
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    Can you tell if that recline motor (#8) has only a power plug on it (no additional wiring for internal potentiometers)? If so, it may rely on an external potentiometer (such as #13) for position feedback/memory.
     
  17. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy
    I guess my potentiometer quest ended after reading Rustybits (Professional Ferrari Technician) answers to this post : https://www.ferrarichat.com/forum/threads/456-seat-operation.147708/

    “If the seat operation restarts after disconnecting and reconnecting the seat e.c.u it's the pontentiometer at fault.”

    My seat operations won’t restart after disconnecting and reconnecting the seat ECU, so I guess what caused this tilting nightmare is not the potentiometer either.
     
  18. Qavion

    Qavion F1 Rookie

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    Don't panic... I had a quick read of the manual and I found a few of the missing pieces.

    1) The potentiometer is associated with the seat back recline function (as I thought earlier).
    2) The other axis motors are fitted with Hall-type position sensors which are part of the memory system
    3) The wiring that was missing in my diagram, I found on a separate page in the manual (but I'm still sorting it out)

    I also misunderstood your problem. I previously associated the potentiometer with the seat back recline and when you started talking about the potentiometer, I thought you were referring to the seat back recline system:

    In this case, you need to be looking at the motors at the front of the seat (which have hall sensors inside them).
    I see now there is a motor for raising/lowering the back of the seat base and another motor motor for raising/lowering the front of the seat base. I'm assuming these motors operate at the same time ... i.e. one goes up and one goes down?
    Since your seat is reclined in the forward position, I assume the front motor might be the biggest contributor to your downward facing seat i.e. motor "1A" (in the Eurospares diagram). You marked a motor in your first post, but it's the one above that. Can you get to the power plug on that and apply power?

    I'm not sure why Ferrari didn't include a Hall sensor in the seat back tilt and use such a fragile potentiometer instead.

    Regarding Rustybits' comment, I wonder if he was referring to the potentiometer interfering with the memory function and easy entry (backseat passenger) function, rather than manual control of the seat base tilt?
     
  19. Qavion

    Qavion F1 Rookie

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    In summary, there are actually 4 "potentiometers" (3 are Hall Effect sensors) assigned to 5 motors. There is no potentiometer for lumbar adjustment:

    1) Seat back tilt movement potentiometer (the one at the back of the seat in your first photo)
    2) Seat fore/aft movement Hall sensor (rearmost motors). The motors appear to be in series and depending on which motor or combination of motors are powered, the speed can be adjusted. There is only a single sensor for these two motors (sensor wiring located between the motors)
    3) Seat base tilt movement Hall sensor (fitted to front-most motor, lower one) which raises/lowers the rear of the seat.
    4) Seat base tilt movement Hall sensor (front-most motor, upper one) which raises/lowers the front of the seat

    Hall-effect sensors have no moving parts and are usually reliable.

    I'm wondering if one of the Hall sensors in your base tilt motors has failed or is not getting power (or an earth). Without a position feedback signal, the ECU may play it safe and shut down the motor. Can you apply power directly to the most forward motors (individually)? If not, you may be able to access the main plug"M6" at the front of the seat and apply power there or check for power when the motors are activated. Plug "M9" carries sensor data and sensor power (excluding seat back recline potentiometer power).


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    Here is a revised wiring diagram.

    https://www.dropbox.com/t/KW5ocS0fQ0yLAV7g

    Unfortunately, Ferrari has made a few errors and oversights and not all of the wiring can be resolved. Some basic voltage checks on the car may resolve this however.
     
  20. Qavion

    Qavion F1 Rookie

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    Here's a typical Hall Sensor (according to Google)

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    Ferrari uses brown and orange wires for power and earth. I just haven't figured out which is which yet. Brown is sometimes used for power and earth, but orange is unlikely to be an earth, so I'm guessing orange should have 5 volts on it (at all times) with power going to the seat.

    Suggestion: Check for 5 volts on all orange wires on plug 9M.
     
  21. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
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    #18 456enthusiast, Nov 23, 2020
    Last edited: Nov 23, 2020
    Ian, thanks ever such a lot for your help, much appreciated.

    I was indeed referring to the seat back rest recline (not the seat base). The motor and plug associated would be to be motor 8 (Eurospares diagram) and plug 7M (in the first diagram you posted)?

    Cheers
     
  22. Qavion

    Qavion F1 Rookie

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    There are quite a few plugs involved.

    7M is the seat control panel on the side of the seat
    6M has the power wires for motor 8
    10M is the potentiometer

    Review:
    ECUs swapped, so the problem has to be wiring, motors, control panel/switches or sensors. Or a calibration issue.

    Potentiometer:
    Power for the potentiometer comes from the ECU (pin 17, red wire). I believe the brown wire is the earth wire which goes to pin 16 of the ECU. The middle contact of the potentiometer is the one used by the ECU (ECU pin 40, yellow wire) for position. You say you've swapped the ECUs, so I'm assuming you can get to the ECU plug relatively easy? If so, you can do a lot of wiring checks from there.
    If the potentiometer is like the F355 seat potentiometer, it has an approximate range of 100ohms to 4k ohms if I remember correctly.

    Motor:
    If you can get access to 6M, the power plug for the motors, you could not only run the motor using direct 12 volt power, but check things like motor winding resistance. We now know that there are no internal switches or relay inside the motor which should prevent it running. If it doesn't run with 12 volts, then it has to be a motor or mechanical issue.
    Figuring out which pins to put power on or check might prove difficult unless you can trace the wiring the motor.

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    Ferrari doesn't tell you if you're looking at the front or the back of the plug.
     
  23. Qavion

    Qavion F1 Rookie

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  24. Qavion

    Qavion F1 Rookie

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    Just wondering how easy it is to detach the drive cable from the motor


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    If you can hear the motor click, but nothing happens, maybe the drive cable has frozen (or the gearbox at the end of the drive cable has frozen).

    Having said that, how smart is the motor control? Would it shut down the motor if no real movement is detected (via the potentiometer).
     
  25. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
    94
    UK / Italy
    Hi again Ian,

    I shall pass this infos on to the electrician guy who’s helping me with this; thank you.


    Some considerations:

    All the internal m/switches on the seat side do work. The ECU works.

    The seat first titled forward while I was driving the car (needless to say, without me touching the tilt lever). Considered that the motor did fold the seat in the first place, am I wrong thinking that either the motor or cable 9 work fine as well?

    I understand next to nothing about electrics so consider the following questions like they were coming from a four years old, I won’t be offended :)

    Would disconnect the potentiometer switch (pic 1: this white plastic switch in the back of the seat) make any difference?

    The electrician suggests to apply the 12V power by connecting the pins to a car booster. Could the Ampere difference (if any) damage any of the circuits?

    Lastly, there seems to be only to two wires coming out of the motor (pic 2), shouldn't the 12V power simply be applied on these?

    Cheers
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  26. Qavion

    Qavion F1 Rookie

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    #23 Qavion, Nov 24, 2020
    Last edited: Nov 24, 2020
    Ah, ok. Sounds like the motor and cable are ok. I guess that helps reduce the number of possibilities. I don't think the potentiometer would cause the seat to move randomly. It's more likely to change the range of operation of the seat back (If the potentiometer wasn't calibrated properly, the seat may hit a physical limit or stop in the wrong position).

    If the seat moved by itself, it could be a false signal being sent by the seat control panel to the ECU. Looking at the wiring diagram, you only need an earth on the green (or purple?) wire going from the control panel to the ECU to move the back of the seat. I haven't figured out yet which wire is which direction.

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    Yes, you can put power directly on the motor pins. The motors normally use 12 volts, so you will be ok with a booster or spare battery. You just have to figure out a way of putting the booster wires on the pins/sockets without shorting the booster leads together. If the seat doesn't move, reverse the red and black wires on your booster to change direction.

    By the way, regarding the photo you posted of the motor, those two wires go to the white multi-pin connector at the front of the seat (on the left side of the forward-most motor). i.e. M6
     
  27. Qavion

    Qavion F1 Rookie

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    Here's my latest driver's seat diagram (version 4):

    https://www.dropbox.com/t/Vp50Naz07feMcJXk

    Probably won't help, but I've added some wiring going to the seat (power wires, memory panel wires, etc). One of my other 456M diagrams has this additional information, but I thought I'd put all the wiring on one big diagram.
     
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  28. 456enthusiast

    456enthusiast Karting

    Jul 23, 2011
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    Downloaded this diagram too. :cool:

    If I understand well, we have to ways to try move the back rest:

    Applying 12V on the pins of motor 8

    Using an earth on the green (or purple?) wire going from the control panel to the ECU

    Is that correct? :rolleyes:
     

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