Did that work?

I had the same problem on my GenII. It turned out is was the diaphragm on the underside of the reservoir cap was being sucked down, pushing on the float and switching on the light. I figured the brake fluid must be expanding and contracting a lot and therefore contaminated. I changed the brake fluid, pushed the diaphragm back in place and the light has been off ever since (over a year).

That may help.

'97 Montero 'LSR' - 4.6 gears & factory rear locker, 33" Procomp muds on 15x8 steelies, 50mm coil spacers, T-bar crank, Airlift, sans rear sway, 50mm rear frame & fuel tank lift, Aisins, ARB front bumper + 10k lb winch, 50mm DIY body lift, rock sliders, cut rear quarter panels...