The brake pads on a Toyota 4Runner need to be changed every year. Usually, this is because the pad material grinds down to about 1/8 inch thick. At this thickness, the pads will have a hard time gripping the brake rotor. When you notice a vibration or "shimmy" in the steering wheel while braking, this will be a clear indication that the brake pads on your 4Runner need changing.
Loosen the lug nuts on the wheels you'll be working on. Turn the lug nuts 40 degrees counterclockwise with a tire wrench.
Lift the 4Runner off the ground and put it on jack stands. Use the floor jack to lift up on the front and rear (if needed) jack points. On the 4Runner, these will be the front and rear cross member. Place jack stands underneath the front and rear pinch welds, and lower the 4Runner onto the stands.
Finish removing the lug nuts, and pull the wheel off the hub. The wheels may be stuck on there, but if you give them a good kick at the top or the bottom, you should be able to pull them right off.
Slide the c-clamp over the caliper assembly, which will expose the back of the outboard brake pad. Put the screw-end of the clamp against the outboard pad and the other end of the clamp against the back of the rotor. Tighten the clamp to push the caliper piston back into the caliper. You can't see the piston at this point, but you will see a space developing between the outboard pad and the caliper bracket. When the piston bottoms out in the caliper, stop tightening the clamp.
Remove the caliper pin bolt and upper and lower mounting bolts. The pin bolt is the bottom-most bolt on the caliper. The mounting bolts connect the caliper to the wheel hub.
Slide the caliper off the brake rotor.
Open the caliper from the bottom and pull out the brake pads. Then, insert the new pads.
Reassemble the caliper. Assembly is the reverse of disassembly. Make sure that when tightening the bolts, you put a dab of thread locker on the threads of all bolts. Tighten the pin bolt to 23 lbs.-ft., and the mounting bolts to between 50 and 55 lbs.-ft. depending on the year of your 4Runner.
Spray the caliper and rotor down with brake parts cleaner to remove any oils from your fingers and dirt.
Put the wheels back on, lower the 4Runner to the ground, and tighten the lug nuts to 100 lbs.-ft.