355 Spider Top not opening: another one for the problem solvers

Ian and Mitchell, thanks for the responses. Although I have not seen the Jaguar pot fix, I did glue my driver side pot back in 2012 (right or wrong) and it has been perfect ever since.

I was able to find my notes from 2012 and retrieved the resistance (ohms) settings for the pot with the seat full forward. Here are the comparisons:
2012: YEL-BLK=2.43kΩ; YEL-RED=5.47kΩ; BLK-RED=4.57kΩ
2019: YEL-BLK=0 kΩ; YEL-RED=4.53kΩ; BLK-RED=4.53kΩ *

*Note: My old notes indicated seat full forward equated to maximizing the ohms on the YEL-RED pair. I accomplished this today by rotating the gear wheel fully clockwise. The YEL-BLK resistance appears to be the inverse of the YEL-RED reading, that is, it maxs out at 4.53kΩ when rotated completely counterclockwise. Oddly, the BLK-RED pair's resistance holds steady at 4.53kΩ regardless of how I rotate the gear. Could this be a clue?

Other meager troubleshooting attempts indicate the following:
(1) I turned off the battery for a few hours last night and turned it back on.
(2) I checked the 10A AC fuse in the footwell to confirm it was fine. It was.
(3) With the seat removed, I tested for DC voltage at the motor connector (2 wire connector - lt. blue and white). I did this with the potentiometer connected (set both full clockwise AND full counterclockwise) and with the potentiometer disconnected. With key turned to accessory, driver seat moves normally but I do not get any voltage when pressing the passenger seat switch in either direction. The switch does light up like the driver switch.
(4) The wiring harness under my passenger seat also includes a small part (#167924) that looks suspiciously like an inline fuse holder. The parts diagram calls this part only "BRACKET." It appears to be a solid molded piece with no way to crack open and inspect. What is this piece and could it be a clue?

I am out of ideas for the moment...

 

In theory, for any potentiometer, the sum of the two smaller potentiometer readings should approximately equal the larger one. Regarding your 2012 values, the sum of the two smaller readings do not equal the largest reading. Yellow-black (2.43k) + yellow-red (5.47k) should equal black-red. It doesn't. Was your potentiometer broken at this point?

Your 2019 readings, however, do make sense (in the fact that the two smaller readings = the largest reading). The fact that red-black doesn't change is a good sign. Normally, you would assume red was power and black was earth, however, on my car (at least), this is reversed. It may be a right hand drive/left hand drive thing? Anyway, I've altered my diagram to show my car (RHD).

If you look at the wiring diagram's passenger's potentiometer ("P2") wires:

Roof wiring diagram (5.2)

The (white-yellow to black-blue wire) reading plus the (black-blue to black wire) reading should equal the (white-yellow to black wire) reading.
When the sliding contact (arrow) in the potentiometer moves up or down, you are changing the resistances between the centre wire and the outer wires.

I looked under my passenger seat car and I found a plug with a black-white and orange-white wire on it. I'm not sure what that is attached to, but it just looks like a jumper wire. There is an orange- white wire in the roof diagram attached to a jumper which puts a permanent earth on the roof controller's pin A11, but I'm not sure what its function is.

I assume your car is the same as mine (in that the switches are always illuminated with the ignition on)?
The symbology in the wiring diagram for the switch circuit is a little confusing to me. Originally it showed power permanently going through both internal contacts to the seat back/forwards pins on the roof controller, but that would be silly. I've just changed my diagram, but now the power is going through the LED to both seat back/forwards on the roof controller. I don't know if this is an improvement or not.

Let me get back to you on this. We know you seat switch is getting power, but is the switch functioning ? Having both fore/aft seat contacts fail is not likely though. Have you tried swapping the switch plugs anyway?

 

Could you just clarify if your seat motors do/don't run with roof operation? I know this may be difficult with you pulling your seat out and in. If the seat works with the roof, then obviously your manual seat switch circuit is faulty. If both the roof and manual seat operation is faulty, then either the potentiometer has been put in the wrong position after regluing the claw, a plug hasn't been hooked up somewhere or a wire has broken.

Just looking at your 2019 values compared to another gentleman's values (assuming brown is black and pink is red)

I don't know if your 5.5k is significant (vs the other gentleman's ~4.5k). I assume the roof ECU, when calibrated, should be able to compensate for a reasonable variation.

Have you tried manually running the seat with the potentiometer plug disconnected? It has worked for some. Open circuit may be the equivalent of the seat being sensed as fully aft. Of course, it's not advisable to try this if your seat is fully forward to begin with (you'll be trying to drive the seat against its forward endstops).

EDIT: Going back to your old post:

Was this the case just prior to your latest maintenance?

 

Sorry, I just realised that you said you had no movement with the passenger potentiometer disconnected, so disregard this:

Sorry, I should have said "open circuit may be the equivalent of the seat being sensed as fully forward". High resistance on yellow-red = seat fully forward. i.e. your seat may be able to be driven back from this point, but not forward.

From your recent description, the potentiometer resistive circuit seems fine. Assuming the seat is fully forward with the potentiometer installed, your yellow-red resistive value should read close to your black-red value. Your yellow-black value should read close to zero (or, say, 0.5k ohms).

Assuming your motor hasn't suddenly died (or the black-coloured motor electrical plug hasn't been reconnected properly), it must be a control issue. i.e. either the passenger side manual switch is faulty or something in the roof controller has broken. Have you seen this message thread?

https://www.ferrarichat.com/forum/threads/96-spider-power-seat-not-working.552975/#post-145395888

Hopefully your roof controller is in better shape than Roger's.

I ordered some roof controller seat relays as a future investment.

 

I didn't realise that both seats had those shorting plugs. I disconnected both (at the same time) and manual operation of the seats seemed normal. Two shorting plugs are not shown in the diagram, so I don't know what is going on. I checked the resistance of the pins on the shorting plugs (swapping multimeter leads) and there didn't seem to be any mystery devices such as diodes in them.
The driver's shorting plug had an orange-white(stripe) wire and a white-orange (stripe) wire.

I checked the potentiometer values on my car at the extreme ends of travel and got some really strange numbers:
Passenger (fully aft)
red-black = open circuit!
red-yellow = 924ohms
yellow-black = 3940ohms

Passenger (fully fwd)
red-black = open circuit (again)
red-yellow = 4329ohms
yellow-black = 543ohms

Driver (fully aft)
red-black = open circuit
red-yellow = 576ohms
yellow-black = 4218ohms

Driver (fully fwd)
red-black = open circuit
red-yellow = 3742ohms
yellow-black = 1028ohms

Unless some kind of dodgy modification has been carried out on my car, I don't know how the seats operate normally.

I have a '98 Australian delivered car.

 

aha.. operator error.... My Flukemeter 302+ has a resistance limit of around 4000 ohms. Too much above this, it shows open circuit. Remind me to read the fine print.

 

I know this is bizarre and confusing but I tested the the seat motor connector during top operation while manually changing the ohms of the potentiometer by spinning it in both directions. With pot fully CCW (lowest ohms) the connector showed 12V at the beginning of top the opening process. Conversely it showed 12V with pot fully CW at the end of the top closing process. So I knew the motor was getting juice during the open/close process via the main console switch.

Then I tested the passenger seat switch with the multitester at the same motor connector. No voltage clicking forward or back. I swapped the driver switch into the passenger seat connector. No change. This ruled out an issue with the switch. Next was testing the motor...

After rigging up some wiring with a 10A inline fuse I applied it to the motor with the seat out of the car. Seat moved perfectly in both directions. Now here is where it gets interesting.

Ready to reinstall the passenger seat, based on my testing I fully expected the seat to operate during the top open/close process but NOT with the seat switch. I installed the seat and now the seat worked perfectly with the switch and top operation is normal! How did this cure itself? I have no idea. Perhaps some old connections were improved via removing and reconnecting some of the connectors. [EDIT: My working theory is the potentiometer started all this erratic behavior. Since the ball-and-socket gear is a friction fit from the factory, I believe that a couple of broken "claws" on the plastic socket enabled intermittent ohm readings--therefore allowing the top ECU to have correct data on seat position at some times and incorrect data on seat position at others.]

Final chapter (hopefully): striving for perfection but not wanting to tempt fate - there is one more bit of fine-tuning before I am truly happy. I realized my passenger seat does not go quite far enough forward with either the dedicated switch or with the top console switch. My belief is that this is a result of resetting the potentiometer to the highest ohm setting (fully CW) before manually applying 12v and moving the seat to its true full forward position. So the pot thinks the seat is full forward when it still has a couple of inches to go. I do not want the top frame colliding with the seats (that may cause me to burn the car to the ground at this point) so I plan to yank the seat out one more time, move it to full forward position with a 12v source, THEN set the pot to align with full forward.

It is typical after these troubleshooting journeys for me to have a brief feeling of major enlightenment. But with the 355 Spider top, I must stay humble...knowing firsthand that trial and error combined with loads of patience may pay off. And it may be inexplicable.

 

Sounds plausible.

You don't have anyone near you with an SD1 tool so you can carry out a proper calibration? I assume, with the current memorised settings in the roof controller, setting the pot to align with the fully forward position may mean your seat won't go fully back.

I see DIY-ers have come up with all sorts of solutions to this problem. Apart from glue, here are a few other cheap fixes:

Fuel hose linkage

http://www.oddparts.net/home/ferrari-seat-position-sensor

One gentleman used a soldering iron to create a new groove for the spring clip (higher on the ball).

https://www.jaguarforums.com/forum/xj-xj8-xjr-x308-27/repair-memory-seat-potentiometers-131192/#post1520636

 

My Ferrari technician just informed me that these jumper wires inhibit roof operation. The plug on my passenger jumper wire had a faulty clip. Although it was quite secure without the clip, there might be rare cases on other folk's cars where the jumper wire or plug is damaged inhibiting roof operation.

I've modified my diagram to show the likely setup based on wire colours (There's two orange-white wires on the driver's seat and a single orange-white wire & black-white wire on the passenger's jumpers):

Spider Roof Wiring Diagram

 

Folks.... A gentleman on jaguarforums.com ("nilesh") will be sending me a sample of his latest version of his 3D printed spider seat potentiometer "ball and socket" plastic sockets (i.e. the white clawed socket part). His previous versions have lasted 3 years and are still going strong. His latest version has a harder core and the tolerance is in "nano-meters". He said that he is willing to offer these to FChat members.

Since new potentiometers are no longer available at the usual Ferrari suppliers and when you do find them second hand, the sellers want hundreds of dollars, I wouldn't hesitate to pay a reasonable sum for a couple of these 3D printed sockets (as a future "investment"). He has given me a ballpark figure, but I think he's undervaluing his contribution to the Ferrari and Jaguar community, and, as you may be aware, professional 3D printers are not cheap to run.

Let me know if you are interested in PM and I'll put you in contact with him. IMHO, this seems like a better solution for folks who don't have the skillsets or tools for precision drilling or regluing small pieces of plastic.

Cheers.
(Hope this is not violating the forum commercial rules?)