From your other thread
https://forum.james-cook-freunde.de/vie ... =16&t=7805
It looks like you got a new replacement D4. As posters on that thread said, the ECU electronic control unit in the original D4S is Westfalia specific to communicate with the central computer console above the windshield. See the last postings in this thread below where a replacement ECU was found in Germany, and folks are wondering if it's just a regular ECU with Westfalia software programming and which ECU version.
https://forum.james-cook-freunde.de/vie ... =16&t=7690
BulliFan/Stefan identified this shop:
Eberspächer in Hamburg.
Note that the original D4S has an "S" in the model to designate a special supercharged version of the D4. The D4S has a higher airflow output (and the software may recognize the longer ductwork restrictions so as not to turn off heater)?
Note that the original D4S wiring connectors were cut off by Westfalia and new connectors were used. The new connectors allowed the wiring to be attached on either side of the metal box. This complex solution to routing the wiring harness through the metal box sides means Espar diagnostic tools need a special compatible connector. In the USA, posters have found that OBDIi readers can read the Espar D4S through the OBDII port. (Don't know if Europeans vehicles have OBDII ports.)
With your new D4, you may want to explore:
1. Contact that German Espar shop in Hambirg which sold the ECU to fix an original D4S, and ask if they can program your new D4 ECU to work with the central computer console above windshield (or whether their ECU can replace your new D4 ECU).
2. Buy a new control and wire to your new D4. A new control could be located near the windshield or in a more convenient location to upper bunk.
Please post whatever you find and do. Thanks.