Translator needed for instructions.

[GSR70Y]

Hey guys,
My brother bought a HKS boost guage off ebay but it didn't come with wiring for the light. Having a closer look at the back of the guage there are 2 round plugs, Can someone please tell me what these are for?

 

[Entaran]

Earth and ground for the backlighting possibly... or is it one of those memory units that has a control unit?

 

[GSR70Y]

I presumed that it was a plug to run multiple guages in series like the Link Daisy chain, just wasn''t too sure as they were covered up with a black sticker.

If I can't get the seller to send a harness for the light, would an electronic store like jaycar have the right plug?