Computer needs to see the button on the shifter so I would check the connections from this to the computer. If not then check fluid levels and then possibly have the fluid and filter changed. After that a mechanical linkage adjustment or internal issue.
The 2006 Toyota 4Runner has a 5-speed automatic.
The 2008 Toyota 4Runner has a 5-speed automatic.
The 2002 Toyota 4Runner has a 4-speed automatic.
The 2001 Toyota 4Runner has a 4-speed automatic.
The 2003 Toyota 4Runner has a 4-speed automatic.
The 2007 Toyota 4Runner has a 5-speed automatic.
The 2004 Toyota 4Runner has a 4-speed automatic.
The 2009 Toyota 4Runner has a 5-speed automatic.
The 2005 Toyota 4Runner has a 5-speed automatic.
The 2010 Toyota 4Runner has a 4-speed automatic.
The 2014 Toyota 4Runner has a 5-speed shiftable automatic.
The 2012 Toyota 4Runner has a 5-speed shiftable automatic.