OK, this is drawing on info from above, and a little Olds thrown in for fun, but have you tried holding down the switch to the high beams while someone watches from in front? If the lights continue to flicker/flash, you can rather safely assume its in the first half of the harness. If there is a noted change, bypass the switch for a few minutes, and run a amperage test. Excessive draw means you are grounding out on the frame in more than one spot. Give it a try, this helped on my Olds.