My XJS drivers electric seats have stopped working, and I’d appreciate any pointers.

When I got it inspected for import compliance it failed on (amongst other things) the drivers seat electrical adjustment not working.

When it was at the panel beaters (getting some rust removed) they told me that they could only move it one way, forward and not backwards. By the time it got to me, (I hadn’t realised it didn’t work) none of the electrical adjustments worked.

When I got my hands on it, I started tinkering, there was a black wire attached to the switch that was broken, I repaired that, although I’m not sure what function it was associated with.

So I’ve got a few questions.

1) Can you adjust the seat manually? I’d like to test the other components, but can’t access them as the seat is over the seat rail screws.

2) Any idea what the black wire from the drivers side seat adjustment (with memory) switch’s does?

3) What next?
So far I’ve tested fuses, inspected and repaired the switch, tested it again, tested that the control module is getting power.

As always, any help much appreciated.

 

I had two 1994 XJS coupes and never found any 'manual' seat adjustments.
One common fault I have read about are potentiometers along the seat rails.
Someone here might be able to supply a wiring diagram to apply 12 volts to move the seat back.
At least that would eliminate the motor from the equation.
Have you looked underneath the seat for any obstructions?

 

Look in the sticky thread at the top of the page for the 1994 electrical diagram.

 

If you look at the diagram, I think you'll find that the black lead is the earth wire on the seat heater switch?

Common cause seems to the seat potentiometers. But in case it's the ecu signal, you could just try applying current to the fore and aft elements of teh motor. The elec diagram on Jagrepair.com is your friend and identifies the appropriate wires to do this.

Cheers

Paul

 

Thanks for the tips. I am really interested to know how the control unit knows when the seat has reached its end stop.

As far as I can tell, there’s no limit switches, and the potentiometers are used only in the drivers seat, so I assume they are used for the seat memory function only.

Can anyone confirm how it knows when it’s reached its end stop? Possibly monitoring current draw on the seat adjustment motors?