Ok try one thing. Not sure if work, but worth a try.
- Go to some online English-Japanese translation site.
- Write the world English and get it translated in Japanese. 3. Now take a print out of the result and open the navigation screen of your vehicle.
- Try to find a similar word in different menu screens
- If you see a matching word press it.
If the navigation system comes in different languages, it should change.
If it comes only in Japanese (one language) then you cannot.
You can also get Japanese words for language, settings etc and find them in your navigation system, I hope it works.
I don't understand why people are charging so much just for clicking a menu in the navigation system to change the language.