The hi beam dosent have much to do with the dash light.It supplies the headlights and the hi indicator.Id say 99.99% it the reostat on the headligfht switch.Ive had a ton of hi beam switches go bad and replaced and never ever in over 40 years saw one that took out the dash lights.Pull the switch and check for power to the reostat and jumper it to the dash wire.I can just about guarantee they will work.Rocky