Putting in the led signal lights on my 65. Have them all hooked up but a few problems. Both front signals flash at the same time. And back right one doesn't work at all. If I put in old flasher both back ones work with the brake and park lights. right one doesn't work at all with the new flasher. No brake no park light. Has anyone else run into this problem? Have to use the new flasher to flash which makes sense.

 

You almost always have to wire a resistor into the light circuit for LEDs to replace standard bulbs. Without that resistance in the circuit they seldom work correctly. I do not remember the resistor value. Hopefully someone will chime in.

 

and good clean ground contacts are a must as you will get feedback and double lamp lighting as it will seek the path of least restriction looking for a ground hence both lites coming on when one is applicated ..

 

Also it is possible that some diodes may need to be added to control backflow voltage issues