As far as I know, the schemes for the Beta and Gamma headlights are similar. H1s were used for the outer lights on the early models. I think that H4s have been used since the manufacturer improved them.
However, the schematics for both early and late models only show the circuit for H1.
I would guess that the headlights were changed from H1 to H4, but the wiring was not changed.
I have modified my Gamma with a relay so that the H4's are switched on upper beam.
Masataka
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