PWM controller circuit Issue
I took measurements of the 555: Voltage from power supply=12.11v ,
  pin1=0v , pin2=12 , pin3=10.87v , pin4=12.11v , pin5=11.69v , pin6=12v
  , pin7=12.11v , pin8=12.11v . This voltages remain the same no matter
  how I turn the potentiometer...


Those voltages are very abnormal. Here's the internal circuit of an NE555:-



The first thing to note is that pin 5 should be 2/3rd Vcc, ie. ~8.1V. Also if pin 6 is higher than pin 5 then pin 3 and pin 7 should both be low.

So either your wiring doesn't match the schematic, or pin 1 is actually open circuit (which would explain why the other voltages are too high), or the 555 is fried.