74 ECT/Trans Temp Sensor Ratio Error

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Description

The coolant temperature sensor (CTS) is a thermistor located in a coolant passage on the engine. When coolant temperature is cold the sensor has a high resistance, as temperature increase the resistance of the sensor decreases. The PCM provides a five volt signal to the coolant sensor, which is also connected to PCM ground. The PCM reads the voltage drop on the signal line to determine coolant temperature.

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Information Flag Parameters

Information Flag 74 will set if:

  • The transmission temperature sensor is functioning properly.
  • The CTS reading is less than Transaxle Temperature Sensor (TTS) reading
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Diagnostic Aids

  • Information Flag 74 is used to indicate a degrading CIS. Remove the CTS and inspect for contamination.
  • Measure resistance through the CTS by attaching female terminals to the two CTS pins.
  • The resistance reading should be 2786 ohms 40 ohms at room temperature (25°C [77°F]).

NOTICE: Information flags should be used for diagnostic purposes only. They do not necessarily indicate component malfunction/failure.

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