2010 Toyota 4Runner Owners Manual - Page 260

2-4. Using other driving systems Using the rear differential lock system STEP 1 Before using the rear differential lock system: Stop the vehicle, shift the shift lever to N and shift the frontwheel drive control lever into L4 to see if this is sufficient. If this has no effect, additionally use the rear differential lock system. Be sure the wheels have stopped spinning. Press the rear differential lock switch. Gently depress the accelerator pedal. After the rear differential is locked, the indicator will come on. STEP 2 STEP 3 STEP 4 Unlock the rear differential as soon as the vehicle moves. To unlock the rear differential, press the switch again.