Rear Locker

From Faq

TRD Off road equipped Tacoma's come with an Electronic locking differential. The locker fits in the Toyota 8" rear axle. To engage the locker there is a switch on the drivers side dash. The locker may not engage right away, and you'll need to drive forward or in reverse while turning to get things to line up.

Put info about locker motor rebuild here,

Stop that annoying blinking light, build and wire your own Locker Control

Here is a write-up on how to replace that troublesome factory locker control with a simple trouble free switch. It will allow you to engage the rear locker under any conditions regardless of speed. Be careful not to engage the locker at high speeds as damage to your axle could result. Also do not engage the locker on dry pavement at it will put unnecessary strain on the axle and will result in excess tire wear. It is dangerous to have the axle locked when driving on snowy, icy or otherwise slippery road conditions as it will adversely affect vehicle handling.

http://www.norcalttora.com/~dick/Writeup%20Stuff/toyota_elock_control.pdf