I purchased for my 65 mustang the United Pacific sequencing tail light units.
I also installed the United Pacific led flasher with ground wire.
After installing flasher before adding led tail lights everything worked as it should with the old incandescent 1157 lamps.
I then installed the led module and it doesn't sequence no matter what position I turn the left, right, and no sequence settings on the module.
The other functions work, left signal, right signal, & brake.
Problem is that...

65 Mustang LED tail light problems