Low battery indicator in Japanese SW20

I found something unusual I have not seen in manuals or other MR2s in my 1990 SW20 GT import. It has a little light in the dash which looks like a yellow battery with a low fluid level in it. I notice there's a battery low level sensor mounted under the dash, so I'm wondering if the yellow battery light means "low voltage"? The red battery light means low charge level from the alternator, so this was the only explanation I could come up with.
 
While I am talking about the Japanese wiring, does anyone have a <1993 Japanese wiring diagram? It uses much the same colours as the US model, but the pins are all different, and there are extra pins to things like ignition etc and things the US models didn't have. Just would be nice to actually have an official one instead of documenting it all the hard way.
 
Edit: I just realised I have a non-turbo instrument cluster, so I'm not sure if it's Japanese or Australian.