When the brake fluid level drops too low in the master cylinder reservoir, air bubbles can get caught in the lines, reducing the overall strength of the brake fluid column. Getting the air out of the brake fluid column will restore the full strength of the hydraulic brakes. To avoid getting air into the actuator of ABS, EBD, BA, or other sophisticated brake systems, the only way to get the air out of the lines is to bleed the brakes.
Vehicle model example: Toyota FJ Cruiser 2012
Tool needed: Toyota Denso Intelligent Tester It2

Let’s go to the straight point.
1. Connect the Denso Intelligent Tester IT2 to the DLC3
2. Turn the ignition switch to ON position
3. Select “ACTIVE TEST” mode on the intelligent tester main function menu.
4. Connect the vinyl tube to the rear brake caliper.
5. Loosen the bleeder plug.
6. Select “SRMF” to drive the solenoids and bleed air from the rear brake caliper (step F).
NOTICE:
• Do not depress the brake pedal.
• Keep the brake fluid in the reservoir tank above the MIN line during the above procedures.
• Brake fluid is sent through the pump.
7. To protect the solenoids, the intelligent tester IT2 (DST2) turns OFF automatically 2 seconds after every solenoid has been turned ON.
8. Repeat step F until all the air in the brake fluid is bled out.
9. When the air is completely bled out of the brake fluid through the bleeder plug, tighten the bleeder plug Torque: 11 N*m (110 kgf*cm, 8 ft.*lbf)
10. Repeat the above procedures to bleed the other brake line.
11. Turn the ignition switch to OFF
12. Turn the ignition switch to ON
13.  Clear DTC

Bleed Brake Master Cylinder with Intelligent Tester IT2