I'm thinking that might be the reason. Many countries have different sections of the FM band allocated for their country.
Don't know what the Japanese band is but I thought it was shifted from 'normal'.
I am right we have lots of Jap spec wings here . You need to get at the antenna cable either under the rear seat or up at the radio (rear seat is easier) and you just disconnect it at the joint and plug this into on side of the joint and then plug it right back into the antenna again ,then run a live wire up to the live wire on the expander ,, it is so simple to do it .By the way ,they will all do .on ebay they have them listed for different model cars ,but they are all the same ,anyone of them will do the job , Ciaran
CIARAN, IS IT TRUE THAT THE EXPANDERS' WHICH ONLY HAVE A POSITIVE CABLE (NO EARTH) WILL END UP GIVING YOU A "HUMMING" SOUND ON THE RADIO??? I READ IT IN EBAY JUST MOMENTS AGO. ALTHOUGH NEGATIVE EARTH I PRESUME IS PICKED UP FROM THE ANTENNA BASE.