[tc4332]

Thanks to a very generous forum member I now have my hands on a J255.
VAG/Audi Number 4E0 820 043 A
SW 4E0 910 043 A 030

The unit was manufactured by Behr-Hella Thermocontrol GmbH (BHTC) in Lippstadt, Germany. This is not far from the Annual meet in Germany. I spent nine years in the area during my Army service and did know a lot of people there. Unfortunately the electronic guys thereabouts have moved on to a better place (this is the problem with age, everyone passes). I'm still in contact with their family members but none of them work for BHTC so no possibility of sneaking information through the old boys net.

Still can't find a circuit diagram but on close scrutiny I have found two small pads on the printed circuit board that I could solder two wires to. The plastic case has enough space for my remote receiver.
There are a number of openings in the case that two thin wires could pass through. I think this would be the better way to do this mod because the receiver aerial could be placed in a better reception area within the car.
I am a bit wimpish at the moment, it's cold outside, so I'll leave working on the car until later.

Big thanks to my secret donor.