interesting...
when i first bought my m-1010,i had a switch in exactly the same location...only they used a hi-lo light switch like you would use for hi beams on an older truck.
traced the wires,but they went no-where.
the wiring on yours is to light to directly be a cut-off for the batteries...probly going to a relay under the dash or under hood.I wonder what they were used for...thought mine was unique in this respect.must be a canadian thing.
the only thing that rings a bell,is the siren...i removed mine.can sirens be switched directly,or do they need some sort of relay?there was no switch of any kind anywhere on my truck to switch the siren...maybe thats it.