On-Vehicle Inspection

WARNING: This page is about a different car, the 2007 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.

CHECK RADIATOR CAP SUB-ASSEMBLY
1. Using a radiator cap tester, slowly pump and check that air comes from the vacuum valve.
  Pumping speed: 1 push every 3 seconds or more
  
  NOTE: Push the pump at a constant speed.
  
  If air does not come from the vacuum valve, replace the radiator cap.
2. Pump the tester and measure the relief valve opening pressure.
  
  Fig 1: Checking That Air Comes From Vacuum Valve Using Radiator Cap Tester
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Standard opening pressure: 93 to 123 kPa (0.95 to 1.25 kgf/cm ² , 13.5 to 17.8 psi)
  
  Minimum opening pressure: 78 kPa (0.8 kgf/cm ² , 11.4 psi)
  
  NOTE: The above pumping speed is for the first pumping only (in order to close the vacuum valve). After the first pumping, the pumping speed can be reduced.
  
  HINT:
  
  Use the tester's maximum reading as the opening pressure. If the opening pressure is less than the minimum, replace the radiator cap.