Did you test the voltages with the bulb in or out? Sometime you will get a no load reading of 12 volts and still have a problem on that side. With the bulb in and high beams on, check both at the bulb, if the high side still reads 12v that side should be ok. Now check the low side at the connector it should be close to 0 volts, if not you have a problem on the ground side. For these test use battery negative terminal for ground.
