I stand corrected then, i only watched the diagrams and i was misled by that S2102 joint which is linked to the MFU thinking it has a N/O electronic switch to earth in it and forgot that when the door is opened the switch is closed. Unfortunately the diagrams for D1 are not so clear like those for D2...nor my knowledge . Sorry ... in this case the problem seem to be with the earth which should come from the LH door power relay but not with the relay itself as long as the LH seat is working which makes the diode on that path suspect...

Thanks again guys.
Some wiring to check for sure and Discool, you are really cool; I would have been starting from scratch without your input.
BTW the left hand seat does nothing with any combination of doors or ignition positions. That seat has not moved in at least 10 years ( but I cleaned the switches as that is what I found on here before posting this thread).

Cheers

Sorry for my mistake in interpreting the diagram first but after i was corrected by @discool i can tell you for sure that if the left seat is not moving at all first to check would be it's power relay cos it delivers the earth for the driver's seat with ignition on

sierrafery said:

Sorry for my mistake in interpreting the diagram first but after i was corrected by @discool i can tell you for sure that if the left seat is not moving at all first to check would be it's power relay cos it delivers the earth for the driver's seat with ignition on

Click to expand...

Many thanks.
Top people.
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Update.
Firstly, I thought I had sealed up most leaks (sunroof etc).

Working at passenger seat I had lifted up carpet and lent on the foam and water leaked out. I cut the foam out to dry (it was soaked). The floor pan was starting to rot. That moisture when heated could go up to the electronics behind glove box.
Photos in a mo.

Anyway, thanks to you guys I swapped relays over and HEY the left seat worked. After a while even the right seat worked a bit WITH DOOR CLOSED.

Getting somewhere.

Relays were getting warm - thought that odd. Took drivers seat out to clean runners and lube gears etc. Tested all motors.

Will fit new relays next. Pulling one apart sort of made it work a bit but not properly. I.e. drivers seat went fwd and back (with door closed!) and then only fwd ( hence taking seat out)

So relays seem to be causing problem as you guys said (thanks) plus drivers seat may have been a bit gummed up. All nice and free now.

300tdi seats more