Where is the backup light switch located on a 2011 ford ranger manual transmission

SOURCE: 2005 ford focus back-up lights not working

The switch is on the gearbox, But not sure of the exact location for your model. But guess there are not many other wired items on the gearbox.

SOURCE: Backup lights in Ford Exp 2002 will not come on

on the side of tranny where shift cable connects is the transmission range sensor or also called the MLP,this sensor could be the cause of no backup lights.
the door ajar switches are located in the door latchs.door ajar switches stick alot,spray WD-40 into all door latches,then open and close doors several times,if switch is only sticking this will cure problem.

SOURCE: 1998 Ford Ranger XLT turn signals, hazzard flasher not working

wire plugin on back of turnsignal switch not making a connecting

SOURCE: reverse lights will not work

look uder the bumper

SOURCE: 2004 Ford Ranger. My brake lights won't work.

Ok it was important to know if 3rd brake lamp was working so we would know where to start.
Since it is not then you will have to first check for power to the brake lamp switch on the pedal itself. You should have power on the LG/RD wire which comes from fuse 19 (20 amp) in the interior fuse panel. When you press pedal down power should then be on both sides the LG wire also. This then goes to fuses 42 (7.5amp) for the left rear and fuse 38 (7.5 amp) for the right.