Toyota Highlander Service Manual: Differential system (4WD)

Differential

...

Precaution

 Before disassembly, clean the outside of the rear differential assy and remove any sand or mud to prevent it from entering the inside of the assembly during disassembly and installati ...

More about Toyota Highlander:

If a warning light turns on or a warning buzzer sounds
Calmly perform the following actions if any of the warning lights comes on or flashes. If a light comes on or flashes, but then goes off, this does not necessarily indicate a malfunction in the system. However, if this continues to occur, have the vehicle inspected by your toyota dealer. Warnin ...