www.jec.org.uk

I have been experiencing an unusual intermittent problem with the driver's seat in my XJS. Every now and again it decides to "automatically" adjust the back of the seat down to a laying position. This as you can imaging is a little disheartening whilst licking down the motorway at a rapid rate of knots.
I have replaced the door switch to no avail.

Has anyone out there experienced this unusual ability that my wonderful XJS seems to have
If so perhaps you could advise me how to stop it as the joys of suddenly laying down for a quick nap whilst blasting down the motorway is becoming tiresome

Blessings,

Aristocat

Aristocat
This must be an unnerving experience!
For safetys sake I would immediately adjust the seat to the preferred position and then pull the fuse whilst you investigate further...........

service manual for six cylinder cars advises (assuming RHD):-
If non-memory this should be No1 Drivers side (above your knees) yellow 20 Amps or for memory seats as above but light blue 15 Amps.

If you have the vehicle handbook this info is worth checking as I have found the maintenance manual to be less than accurate with regard to fuse locations in the past. (the owners handbook is invariably correct).

I am afraid I cannot offer any insight into what the fault is other than if memory seats is it returning to a programmed/default position? If a programmed position re-program it to your preferred setiing.

Good Luck
DH Dove
PS Webman - can this post be moved to "Electrics"?

I think I read about a similar problem which was caused by a sharp object getting embedded in the wiring loom.

Might be worth getting that carpet covered metal plate in front of the seat out and examining the harness underneath?

I had the problem on both seats, fault was with the seat/mirror ECU located in the footwell just in front of the seat.
You could try checking the switch pack, and cleaning the connectors to the ECU. That cured mine for a bit, but problem came back a year later.
Got a second hand spare from www.grublogger.co.uk

Just for the record. I had this problem many tears ago. In my case what had happened was that water from the air con condensate system had collected under the seat effectively playing havoc with the ECU and wiring. I dried it all out sorted the drain problem and all was well.

With me, I had stopped the car and selected reverse. My seat back moved forward, with some force. Quite and experience and definitely not something you would wish to experience whilst on the move.

Nick

OUCH!!!!!
DH Dove

After many attempts to fix the same problem I think I have finally done so !
The printed circuit board inside the seat control module can short down to vehicle earth through copper Rivets that hold the metal fixing brachets to the plastic case. Simply remove the control module from under the seat, remove the scews that hold it together. Fix some electrical insulation ( I used two rubber pads) on the top of the fixing rivets to prevent the PCB from touching them. Then reassemble

Aristocat,

I had a similar problem with the driver's seat on a 1992 XJS Facelift model.
The seat suddenly decided to move forward under its own will and squashed me flat against the steering wheel at about 35mph. I somehow managed to get to the side of the road and stop. After I had finished shaking I found that I could force it back into position by brute force; by pushing the seat backwards with my feet against the toe board.

The local motor electrical specialist SEAC found that where the electrical cable loom passes through the rear bulkhead, there was no grommet. The cables had worn bare and were hot and sparking. Fuel in a plastic fuel pipe also passed through the same hole in the bulkhead.

As a result of SEAC’s searching, Jaguar supplied a new loom piece and a new steel fuel pipe was fitted in the area which overcame the problem.

Regards,

BrianH