At 36,00 miles my 2012 Jeep Grand Cherokee left, rear turn signal went out. It was very simple to replace. (This also applies to 2011 and 2013 models)
1. Acquire a 3057 replacement bulb
2. Open the tailgate
3. Use a flat blade screw driver to pop out both retainer pins.
4. Pull the whole tail light assembly straight back
5. Rotate the bulb holder to the left and remove from the assembly
6. Pull the old bulb straight out
7. Push the new bulb straight in
8. Reinsert the holder and rotate it to lock it back in place (an arrow and the word "lock" are molded in the housing if you forget which way to turn it.
9. Line up the two rear alignment pins (the two black posts towards the back of the assembly) with the two sockets in the car panel and push the assembly straight forward (towards the front of the car) to seat it securely back in place.
10. Insert the two retainer pin bases, then push the two pins in place.
----> Problem solved in 5 minutes for $5