i have similar problem i have a r33 gts-t my rev meter dies and hicas light comes on at the same time and comes back on again, ive pulled my cluster out and gave it a good clean pulled all the plugs out and put them back in, the problem is still there. Theres no modification done to the hicas and i dont have any after market tachos. I think the best place to pin point the problem will be auto electrician