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12.14 - Fuel Fail 14 : coolant temp sensor out of range ( Brett Gadzinsky,  )

Conditions for flagging :

After cold start, signal to ecu under 3.53 volts after 6 minutes.
Normal engine operating temp, Signal decrease of .7 volts or greater in 196 milliseconds.
Normal coolant temp sensor out of operating range, Under .1 volt, above 4.9 volts for 64 milliseconds or longer.

If FF14 is flagged, the ecu defaults to 80F.

Possible faults:

- High resistance connection between the sensor and the ecu (dirty connection at coolant temp sensor)
- Open or short circuit in wiring between coolant temp sensor and ecu.
- High resistance ground circuit in ecu circuit.
- Defective engine thermostat.
- Defective coolant temp sensor.

The coolant temp sensor has 2 wires, and is located close to the engine thermostat. They very rarely fail.

The coolant temp sensor is used to control a number of functions:

- Cranking enrichment,
- Warm up enrichment,
- Acceleration enrichment,
- Air injection,
- Idle speed control,
- Exhaust gas recirculation,
- Evap system canister purge.

To test the coolant temp sensor, measure the resistance between the two terminals hot and cold.

14F 9200 ohms
32F 5900 ohms
50F 3700 ohms
68F 2500 ohms
86F 1700 ohms
104F 1180 ohms
122F 840 ohms
140F 600 ohms
158F 435 ohms
176F 325 ohms
193F 250 ohms
212F 190 ohms


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