Hello.
Tricky.
See:
https://toyota.epc-data.com/regius_ace/lh119v/114894/body/8401/
and scroll down to the second image in Scheme 12. I think it’s ‘PNC 84261C’ and clicking on that will take you to Amayama for purchase or try your local Toyota dealership (now you also have the OEM part number other sites / places might be fruitful). It seems to be unique to the H100 but this would surprise me. I like my auto assist door close, too. I think it’s the different lengths of pins that actuate it and end the closure but am not certain of this. Can you repair (re-pot in resin?)?
Modify that Toyota-EPC link for your exact van and you can then search for each and every part. Happy hunting.
There will also be a ‘module’ (jam-packed with state of the art 1980s electronics) to control the system. These are also detailed in the Toyota-EPC (electrics sections) plus the various manuals on the “Hiacesoutheast” site show their location. More happy hunting?
Cheers!