For these 2 LEDs you should use the parameters:
They are working as default, when the suction_1_ratio or suction_2_ratio falls below 1.0 in/hg with any loaded aircraft.
But, as the Laminar B58 includes their own datarefs "/inst_press_fail" for these lamps (though default SimVim worked too), I have remapped parameters to them, but forgot to remove default conditional range.
You need to download the updated SimVim.dat file. All works OK now with B58 too.
P.S. - when watching the dataref list don't look at the datarefs marked as for 660+ or that are located in the ../cockpit/.. section. They are mostly all deprecated. See the ../cockpit2/...