Second Brake Piston: Inspection

WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT 2ND BRAKE PISTON RETURN SPRING SUB-ASSEMBLY
1. Using a vernier caliper, measure the free length of the spring together with the spring seat.
  Standard free length:
  
  16.61 mm (0.6539 in.)
  
  Fig 1: Identifying Free Length Of 2nd Brake Piston Return Spring
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002