2000 CHEVY BLAZER /Any GM One high beam headlight Not Working,IT IS NOT a bad Bulb Or Bulb Harness, No Power?

I Tried A New Bulb,, Should have tested for Power at Plug-in 1st, No Power to Right High Beam,, Tried Jumping a wire over from the working High Beam and spiced it in, Then Both Lights were dim and after 30 seconds or so they Both went OFF,.. Disconnected the splice and the left came back on,. They must be fed separately from the dash switch or a relay,,. But How to test without spending $$ I don't Have on a Part I may not need??