Led lights

[Dfresh]

Ok so I have put some led bulbs in the tails of my 12 Sierra now I have some weird shit going on when the running lights are on and ht the brakes only one side lights up turn lights off both sides work but noticed my fog lights come on and so do my lic plate lights what gives has anyone else had this issue I also have my fogs hooked up to running lights not sure if that has any play in this or not

[O_J_Simpson]

One does not simple put LED bulbs in tail lights...

[Dfresh]

What do you mean by that

[Colossus]

Meaning that the electronics on modern day vehicles like your truck are overly sensitive and require precise specs when it comes to measuring power and resistance and stuff I don't know what i am talking about which results in things not working right like you are describing when you put in LED bulbs. There are things where the LED bulbs will work just fine in and other things where they won't. Hopefully someone else will chime in on what you need to do to fix the issue. Newer vehicles are not as plug n play friendly as the older ones.

[sk]

1. Flip some of the bulbs around 180 degrees. LEDs are polarity-sensitive.

2. You need load resistors installed. Your 2012 does not have the right wiring to just plug in LED bulbs.

3. What others above said. You can't just plug LEDs into an older vehicle and expect them to work. Also you mention fog/running light changes that you made. Nobody knows what you plugged inline or what you did to the electronics of the vehicle.