The first generation Alphard, being JDM from the early 2000s, uses non-standard OBD settings.
For engine management, the following seem to work:
Protocol: ISO 14230-4 (5b init, 10.4k baud)
ELM327 custom configuration string: ATIB 96 \n ATIIA 13 \n ATSH8213F0 \n ATSP4 \n 0100