New guy... LED issues

[cmomola]

Hi all! I just wanted to introduce myself and share a few photos... I bought my square body when I was 18 and she has stayed pretty much original. First pics are when I first got her around 2007. I've recently started taking off the old and preparing it for new. One of the main things I wanted to do was change over to LED lights. Everything works until I run the truck with the headlights on, then the rear tail lights blink once and stay solid. I've already swapped the relay, grounded it, and reversed polarity... Any suggestions?

 

[Moodyalaskan]

If the front only blinks once also, the LEDs are probably not drawing enough power to heat up the blinker relay enough to let it blink more. You will need a resistor to give the blinker relay enough to heat it up and continue blinking. The system thinks you have a turn signal out, and it will not continue flashing.