Look for a bad ground to the headlights.The ground probably feeds all of the front lights,and when you are using the headlights,they are seeking a ground through the turn bulbs.When you apply 12v to the turn bulbs,it is reversing this affect(the turn bulbs are seeking a ground through the headlights).
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Look for a bad ground to the headlights.The ground probably feeds all of the front lights,and when you are using the headlights,they are seeking a ground through the turn bulbs.When you apply 12v to the turn bulbs,it is reversing this affect(the turn bulbs are seeking a ground through the headlights).