I just changed the drivers seat in my XJR to a different seat and the power function is working intermittently.

I assumed power control module under the seat...changed it with my GOOD working one and the seats moved...however, when the seats are about halfway slid back, the seat stops working. No functions work whatsoever except for the lumbar support.

Changed the switch itself with my GOOD one, still doesn't work.

IF I DISCONNECT the seat control module from the seat and reconnect it, the seat power will work again. HOWEVER, again as I said, when I move the seat and it reaches about the mid-way point for sliding forward/backward, it will have no power once again.

The seat module that came with the seat has no broken copper traces. The known working one from my old seat has no broken copper traces. Old power module works properly and powers my old seat just fine. So I know the power module AND the switch on the side of the seat itself is NOT the problem.

I also changed the relay on the bottom of the seat. Again, the module works until the midway point, then absolutely no adjustment at all...front/back or recline.

Connectors are ALL fine, wiring is NOT frayed anywhere. If it was shorting it out, then disconnecting the module and reconnecting it would not get the seat working again.

I'm at a loss here. Anyone encounter this before???

 

In addition, the seat is from a 2001 VDP with 50k miles. Again, if I disconnect the white connector that leads into the floor and then reconnect it, the seat power works again. My old seat worked just fine sliding and reclining.

 

Have you tried your original module fitted to the new seat? I wonder if the runners are bent and a cutout prevents damage?

 

Since you changed the seats and had the same problem, I would look at grounds.
Not just open or closed, but measure the resistance. An electrical circuit will work
very erratically with a bad ground.

 

The original module is the one thats in the car now. I have been at it for almost 3 hours today trying to figure it all out, swapping out all the electrical components. The only thing I havent done is swap out the motors and I find it highly unlikely that they are bad. Or even if one was bad, the others would still work fine.

 

Where would the grounds for the drivers seat be?

 

Could you just mount the new seat on the old frame? I haven't tried that with an X308, but thought I'd mention it.