I have a 06 dodge ram, it started having issues a year ago. The turn signal acted all kinds of weird, I would press the lever down for left and the right light would flash. I swapped out all led bulbs to regular bulbs , replaced the tipm, replace the multi something switch ( turn signal). Problem went away. Now it's back but slightly different .

now when I turn on the driving lights , on the rear of the truck only one side lights up but when I engage the turn signal it flahses correctly. I swapped the left and right lights to see if the problem is the lights or if it's not getting power and it seems its not getting power when I turn the lights on. I have also replaced the light switch .

Sorry for the fast post and numerous errors in Grammer, currently under the truck.🤣

 

Check the rear wire to that rear socket. Do you have voltage with lamps on and the turn signal switch in neutral position. Do you have voltage? If you do, does the voltage go away when use the turn signal switch?