Coolant Temperature Sensor (CTS)
WARNING: This page is about a different car, the 1993 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.
The CTS contains a built-in thermistor in which resistance varies according to engine coolant temperature. The CTS delivers an input signal to THW terminal of Engine Control Module (ECM). The ECM uses input signal for controlling Pulsed Secondary Air Injection (PAIR) system (if equipped), fuel injection system, overdrive operation on electronically controlled transaxles, ignition timing (spark advance), idle speed control system, fuel pressure control system (if equipped), heated oxygen sensor system (if equipped) and EGR system.
NOTE:
Coolant temperature sensor may be referred to as Engine Coolant Temperature (ECT) sensor.