Hi guys, Hoping to find help for the drivers seat problem on my 456M. Every direction works OK besides the forward motion, which goes forward with a click and 1mm at a time... so it takes like 100 clicks of the button to fully move it forward. Now I've read about the potentiometer for the back-tilt function, but it wouldn't affect the forward-backward motion, right? I have put 12V on the motors directly and then it goes perfectly forward/backward. Could it still be some sensor, or ECU? Image Unavailable, Please Login Many thanks!
Opened up the ECU and that looks good on first sight., nothing burned, no weird solder joints. Image Unavailable, Please Login
Apart from the recline potentiometer, the motors have Hall (position) Sensors in them: https://www.ferrarichat.com/forum/posts/147577362/ I'm not sure how you'd go about diagnosing this. The fore/aft movement seems to be controlled by two motors in series (mechanically). There is one Hall Sensor for both of these. Could it just be a faulty control switch? Do you have any seat positions memorised? Do these operate the seats? If you don't have any positions set in memory, can you coax the seat forward, then memorise that position and see if the seats move to the memorised position? Wiring diagram here if you need it, but it doesn't show which pins are which on the control panel (and there are a few loose ends): https://www.dropbox.com/t/0NL2ud5kcfZ5r6Sf
Thanks! Very helpfull. And I'll have to re-check my 12V testing on the seat motors E & D (for-aft)... it's pin 2 positive and 3&7 negative, and other direction 2 negative and 3&7 positive. Think I've only been powering one motor. Maybe fully cycling them back & forth a few times does something. Will check the hall-wiring for good measure.
I don't know why they've wired it up that way except to save a wire. Maybe it's for torque control? One motor = low torque. I thought I'd mislabelled the sensor on motor B. There is only one potentiometer on the seat (and the diagram showed two), but sensor G and motor B are duplicated on the diagram for some reason. Note that Hall Sensors are not checked with an ohmmeter. Testing is completely different. I assume orange (C) is the power wire on the Hall Sensors (5V) and the brown (M) wire is earth. The signal out (pulsed voltage) wire colour varies.
Ah yes, now I see that G&B are also on top of the diagram And indeed, I'll start with checking the wiring for continuity. Thanks, great work on these diagrams! If both motors work OK with 12v feeded (which I think they will), I might lengthen the seat connector harness so I can play with the seat while out of the car, and checking if 12V keeps getting to the seat motors while moving the seat forward. Checking the switch might be a good idea then.
Without knowing which pins on the ECU correspond to which switches on the control panel, the switch checks will be quite tedious. Image Unavailable, Please Login Can you get access to the control panel connector 7M? I'd be curious to know which pins correspond to which switches (and directions). The diagram shows which pins on the ECU correspond to which wires (see the numbers in the parentheses). e.g. (8) 5M = ECU pin 8. The earth pin on the ECU is pin 35
Note that I tried to standardise the pin numbering, but also showed the original alpha-numerical pin identification: B-1, B-2, B-3.... A-1, A-2, A-3.... etc. Can you independently move the front and rear of the seat up and down or do you need to twist the switch (activating two motors at the same time)? I've never spent any time on the V12 cars.
I separated both motors and tested the left and right rail separately... the right side 90° "gearbox" is the verdict. Plastic gear is completely worn, which probably causes the seat to limp forward mm by mm on one rail, constantly jamming. 65877200 is the part number, and seems like an expensive little thing, as to be expected! Anyone got a good one laying around? Image Unavailable, Please Login Image Unavailable, Please Login
C2 Corvette headlamp motor gears used to look like that until aftermarket metal ones became available.
Would be a nice project to make as an aftermarket piece. All the rest is metal and will last forever, so it will always be this that fails...
The last (used) one on eBay was offered at $349. That's probably a sign that they are NLA at the factory. Perhaps 3D printing is the way to go. Some of the V12's have the same seat motors as Porsche, but the drives are completely different.
A friend of mine is going to measure up and duplicate the gear in order to have it ready for 3D printing. Will report progress. Is this a common failure? Might as well make like 25 or 50 to help peope out not having to spend 350-500$ for this little gear.
I don't think it's too common, but it may be more so in the future. Some folks might buy them to keep on standby, depending on the price. I wouldn't make too many, though. I'd take one just to show to my local tech. He's always interested in these kinds of things. Can we confirm that these gearboxes are not available new?
Steve456M - I have a similar problem but not as bad. My seats work in all directions (except for the auto forward/back with seat back tilt lever). But they are sloooooow and sluggish and tired. I've been lamenting on this for months and will in fact eventually pull them out - I'd like to think that just 'cleaning' the motors up and re-lubing them may / hopefully do the trick. BUT, what I reeeeeally want to do.... is put different seats in! lighter weight, newer style, more comfortable, manually moving seats! The only issue...... is the seatbelt. BUT, there may be an answer for that also. On our cars there is fairly significant void under the B-pillar; right behind the door striker is literally empty. between the inner fascia/trim, and the outer body, under the B-pillar is...nothing! It would be a perfect place to smuggle drugs! Or what i'm thinking is a perfect place to put a seatbelt assembly. In fact you could probably use the one off the native 456 seat. (remove it from the seat and install it in the void). Then the belt would come out the top of the trim (via a decorative exit trim piece thingy), and then go over on an angle to the shoulder of the front seat driver/passenger. There's more to think about there but I know it can be done. I'm teetering on the edge of doing this.... I'll take some pics of said void since I have my back seats out right now. cheers
Here’s a pic of that void I was talking about behind the front door and under the B pillar. From inside the passenger side, looking towards the driver side Zoom in… Perfect hidden storage compartment! Or a seatbelt! Image Unavailable, Please Login
Here are some pictures of the 3D printed gears. Took some time and effort, but after a few testbatches it now is a 100% perfect fit, and are made in polyamide reinforced with aluminium for maximum strength and heat resistance. The original worn plastic gear: Image Unavailable, Please Login The new gear Image Unavailable, Please Login Packed with bearing grease, and my seat is working perfectly now! It's the only weak (being plastic) part in the union, so I can see this being present on quite a few 456's. I've had some extras made if anyone needs any, or want as spares. 50€ for 2 gears + shipping. A complete union is crazy expensive, hence why I went this route.
I’m prob gonna take my seats apart in the next couple months. Could you make another batch if needed? great job!!
Just took the pass seat out. My microsensors for auto forward/back work. Need to check the potentiometer. And then clean up the motors. Thats when I might buy those gears from you, if you still have them. Seats are SOOOO heavy! Still considering tge seat swap idea….
