<BIG><FONT face="Verdana, Arial, Helvetica, sans-serif" size=3>Engine Coolant temperature</FONT></BIG></FONT>


<FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>The Engine
Coolant Temperature (ECT) sensor is a two-wire sensor. It is threaded into
the engine coolant jacket, in direct contact with the engine coolant. The
coolant sensor contains a thermistor and provides the PCM with an engine
coolant temperature reading. The PCM provides a 5-volt signal to the ECT
sensor through a dropping resistor. When cold, the sensor provides high
resistance, which the PCM detects as a high signal voltage. As the engine
warms up, the sensor resistance becomes lower, and the signal voltage
drops. Approximate resistance values are shown in the accompanying chart
(figure 3-8). At normal engine operating temperature (85×C to 105×C), the
signal voltage is in the range of 1.0 to 2.0 volts.</FONT>


<FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>The PCM uses
information about coolant temperature to make the necessary calculations
for:</FONT>
<BLOCKQUOTE>

• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Fuel
  delivery
  </FONT>
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Ignition
  Control (IC)
  </FONT>
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Knock
  Sensor System (KS)
  </FONT>
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Idle
  speed (IAC)
  </FONT>
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Torque
  Converter Clutch application (TCC)
  </FONT>
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Canister
  purge (EVAP)
  </FONT>
  
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Exhaust
  Gas Recirculation (EGR)
  </FONT>
  
• <FONT face="Verdana, Arial, Helvetica, sans-serif" size=2>Cooling
  fan operation (some applications)
  </FONT>
  
• <FONT face="Verdana, Arial, Helvetica, sans-serif"
  size=2>Others</FONT>

<strong><FONT color=#0080c0>Figure 3-9,</FONT> Engine Coolant Temperature (ECT)Sensor