I assume that you are talking about the side marker on the front fenders. If you are, and as far as I know, you can't put led's in them without having issues. Those lights don't directly ground to the chassis. That is why they have a dual function in factory form. They are hooked to both the turn and marker circuits. The bulb will ground through the other bulbs in the circuit to work. So for the turn signal, the side marker will ground through the other marker bulbs. When the park lights are on, the bulb is on until the turn signal is on, then it goes out, that is why it will flash opposite at night. You can make it single function by finding which side of the socket has power for the turn signal, cut that wire and make it a ground. That would give you only marker light.
It sounds like the led's that you have are polarized and need a better ground than they get through the 'off' circuit. You may have to turn the led around as well.
I just cut the blue wire and grounded it..
