Inside the potentiometer, the gear is lubricated by sticky grease, so that might be the reason. When cold, the grease gets hard enough for the plastic shaft to hold the gear, but once warmed up, it starts to slip. Just a thought, too...

 

Thanks for the info. Will look at that and report back.
Paul

 

Thanks for the great write-up Japthug! The English translation was perfect and the disassembly and repair instructions are extremely helpful

Now, what's really interesting is that with the clues/info your write-up provided, I did a little "Googling" and found a few things:

- We (Jaguar) are NOT the only ones using these "ball & socket" potentiometers for seat memory that break and leave the seat memory dead.

Seat Potentiometer Repair....NO GLUE!!!...PICS - FerrariChat.com

Fear not the seat pot (potentiometer) How to rebuild one without removing it. - FerrariChat.com

456 electric seat stuck. - Ferrari Life

This last one is pretty funny where the Ferrari guys say that they can save some money by getting the same pot from Jaguar where it is cheaper! I guess it is all relative


- Also, while I appreciate the "sleeve & glue" method in Japthug's write-up (and is recommended elsewhere on the web), here is an interesting alternative right here on our forum:

https://www.jaguarforums.com/forum/x...meters-131192/


Making progress!

.

 

So is it safe to say that if the pots are broken / out of range, the LED and chime will not work?

Like most, my seats work fine manually but when I press the memory button and hold it, I do not get a chime and I see no LED.

Bernie

 

Yes, that is right.
I have to say those pots are made to break!

 

Thank you for the additional info, that is really helpful to know how to access the seat squab pot.


I want to know the price of the Ferrari pot... It must be astronomical!!

 

Hhmm, I get a chime and light when setting my memory but it still only works the steering wheel and mirrors and head rest. If indeed my pots are intact what else could be the problem?

 

Those 3 pots are not prone to break.
The mirror one is controlled by a different way though.
If pots were intact it would be a seat ECU, but I never think all the pots are fine and that the ECU is prone to fail.

I strongly believe that NO X300s without service history of the seat come with perfect seat memory, because of the faulty pots.

An attempt is easier, just unbolt the 4 bolts and check under the seat.
Checking the squab pot is a PITA but the seat lift one is really easy.

 

I have the same issue/symptoms, so I wonder too.

But one theory is that the pots have broken "in range" so the LED/chime still functions but the pots are no longer moving with the seat so they are always "in the right spot" from the pots perspective. I bet if you could get under there and twist one of the pots manually the seat would move "non stop" to its end range for that pot in an attempt to get back to the memory position, which would be impossible as the pot is not turning.

In fact, now that I think about it, that makes total sense when considering my symptoms when I swapped out the used controller. When I hit the memory buttons on the first try, the seat moved to a "memorized position" just fine, but it never stopped .... moving to the extreme range of the motor. Once I rememorized my positions, it never moved again via memory buttons.

I think we are on to something!

The pots are broken. I'm practically sure of it now. Time will tell when I take them apart this spring.

If this fixes this problem, I have to say this will address one of the only problems with this car that really bothers me. I know it is silly, but it bugs the heck out of me when something so simple doesn't work, is a common feature on lots of cars, and should be fixable.



.

 

It bugs the carp out of me when "anything" that came on the car doesn't work as intended. This is the last "bug" to fix on my 97 (I'm sure in no time there we be something else)

 

Yeah, the other two that were bugging me were the "lazy rattling" center A/C vent vanes and the radio.

I found a replacement vent on the cheap with working vanes and all the clips intact, and from the radio thread we seem to have a reasonable theory about the face buttons sticking, specifically the tape eject button.

If I can get the memory seat to be reliable, the vent all fixed up, and the radio working.... I'll be much happier, as I can deal with other mechanical issues as they turn up much more readily.

.

 

Another interesting option is the link below where it appears someone is selling aftermarket pots. No telling how old or current that offer actually is, but...

Ferrari 355, F355 Spider Seat Potentiometer Parts for Sale - DragTimes.com


Also, I have seen offers on eBay for complete seat drive motors for seat motors from an XJS that have the pot attached, NOS for about $60-90. You'd have to cut off the pot and connect it to your plug, or just swap out the guts. They appear to be the same pot from the photos, but one would have to test.


New Old Stock Jaguar XJS 93 5 94 95 96 Driver Memory Seat Slide Motor BEC21090 | eBay

http://www.ebay.com/itm/NEW-JAGUAR-XJS-SEAT-SLIDE-MOTOR-BEC21090-1993-1996-WITH-MEMORY-/361027415750

 

My 96 Vanden Plas. All memory functions work great, except in the last 6 months this happened twice. Driver's back in perfect erect position, when engine switched off and parked and car locked. I would come back later to see the back completely flat almost touching the rear seats like a reclining bed. Did not try to start the car to see if it will come back to normal position. Had to manually use the reclining button to bring up the back rest and then the remote memory functions work fine. Has this happened to any one? What gives?

 

Had a brain fade about whether the X308 suffered the same issue, so thought I'd ask, and they of course do based on my very own post above

This post can be deleted...

.

 

So interestingly, I went to a wrecking yard today to harvest some broken seat potentiometers to repair and replace for my broken ones, and upon pulling a 20 year old pot from the seat, I find that it isn't broken.

So I wonder if some have survived this long, they are good for the long run, while the ones that fail do so early.

I guess I'll put it in the car and see how long it lasts.


.

 

... and pulled out the other three from under the seat, and all almost 20 years old and unbroken. So again, wonder if some just last, and others don't.

I'm wondering if I might want to try to reinforce these with a dab of epoxy where they usually break.

.

 

Sorry to different this up people, I just fixed my memory seat and figured this was the best place to put my "solution". Now this may only help a few people but even if this solves one person's problem it a win haha. I'll put all the relevant information here.

OK so first my symptoms.
No recall at all, seat mirrors steering wheel or mirrors.
No red light or beep when trying to set the memory.
Electric seat works fine.

So all I did was swap the ECU.
The memory ecu had clearly blown up and had been replaced with a non memory module.

Simple I know but worth checking before digging deeper.

The ECU is under the drivers seat, and will be labeled either "memory" or "non memory".

Its worth a check as installing a non memory module is a cheap fix for replacing the memory module.

As a side note, does anyone know if the wing mirror and steering column ECU comes in "memory" and "none memory"?

I need to replace mine.

 

Yep, thanks Harry.

The first step in troubleshooting the seat memory is to look for the red LED and chime to work. If they do not, then replacing the memory seat unit under the drivers seat is the first and cheapest step. The units are very inexpensive on eBay, wrecking yards, etc.

If however the red LED and chime works, and your mirrors and wheel work, then its a clear sign that the seat pots are broken. Another clue is to test the headrest memory. The pot for the headrest is made differently and apparently rarely/never breaks. If your headrest memory works along with mirror and steering wheel, and LED lights and chimes, it is guarantee that your pots are broken. This is also assuming the electric motors also are working.

I can't speak to whether the mirrors and wheel came in non-memory off hand.

.

 

In the hope that you are still on line / alive LOL - might you be able to foward or repost the memory fix from Japthug

PLEEEEEz