[patrickt]

Remember the flasher unit "feeds" the turn signal switch. It becomes intermittent under load. You can jumper "across the flasher" and thereby deliver a constant 12v to your signal switch. If you do that, then signaling a turn will not flash the signal lights on the front and back of the car, but it should still light them (constantly, not flashing). I would definitely test your relays with clean input voltage. You know everything from the back lights to the relay works. Next step is test the relay, then test the signal switch, then test the flasher. That's all that's on the circuit -- you will have gone from nose to toes.