Temperature Control Switch (ECHO)
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2002 Toyota Tundra, 2002 Toyota Tacoma, 2002 Toyota Sienna, 2002 Toyota Sequoia, and 2002 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
On vehicles equipped for cold areas, temperature control switch operates a maximum hot switch which provides an input signal to Engine Control Module (ECM) for controlling Positive Temperature Coefficient (PTC) heater. PTC heater is a small electrical heater located in the heater core. Maximum hot switch may also be referred to as MAX HOT switch. For additional information on PTC heater, see POSITIVE TEMPERATURE COEFFICIENT HEATER under MISCELLANEOUS CONTROLS.