Seat Heater Installation: VW Golf 2 Guide

Hello,
'In my Golf, I still have the switch and wiring harness for the original seat heating from the previous owner. He had leather seats installed until he sold it, but then put the original VW sport seats with built-in heating back in. He had lent those seats out temporarily, and now the seat heating isn't working anymore.'
Okay, so I now have the switch, the wiring harness up to the driver and passenger seats, and two seats with heated cushions. However, these seats no longer have the original cables on the underside. Therefore, my request is:
Does anyone have a photo or wiring diagram of the underside of a G2 seat with heated seats?

The heated seats in the leather upholstery were working perfectly before, so the problem must be with the seats themselves and should be relatively easy to find.
What I also don't know is whether there needs to be a relay and, if so, whether it might need to be located under the seat.

Regards,

Euro.