05 F-150 stereo wiring

Im having a problem trying to put a new amp and sub in my truck. I have looked all over to find a switched 12volts at the radio for my turn on and no luck just keep blowing fuses when i use the multimeter. Also trying to see if i have a factory amp and woofer already, haven't seen any signs of it, but i have the premium 6-cd with mp3 head unit. Also could use the rear speaker wire colors to add a line level output. Any help/ suggestions would be greatly appreciated.

Thanks

If you're blowing fuses using the multimeter then you're doing something wrong.  You may have the red (positive) probe plugged into the wrong slot on the meter.  It may be plugged into the current slot instead of the voltage slot, or you may just be on the wrong setting.  You want to set your meter to read DC voltage (not current) on a scale that can easily read 12 volts.  Touch the black lead to the metal casing of the radio, and the red lead to your suspect wire.

If you have a factory sub, you can use the turn on for the sub amp (should be dark GREEN/ purple).  You can tap the sub wires at the radio- BROWN / orange is positive and RED / black is negative.  The sub and amp are in the driver's side rear corner of the cab.

If you don't have a factory sub, you can use the accessory for turn on- either pink/black or light GREEN/ YELLOW.  Then tap either the fronts or rears for signal (only if you don't have a factory sub):

Test all wires before hooking everything up.