Download Testing - JustAnswer

PATH: Engine Cooling > Coolant Temperature Sensor > Testing
Testing
Animations and Tech Tips
Click to view: Testing an ECT sensor
1. Check the instrument cluster fuse condition and replace as
necessary.
2. Check the sender wire for damage and repair as necessary.
3. Unplug the sender electrical connection.
4. Attach one end of a jumper wire to the sender electrical connector
and the other end of the jumper wire to ground.
5. If the gauge functions properly, replace the sender.
1. Remove the sensor from the vehicle.
2. Immerse the tip of the sensor in container of water.
3. Connect a digital ohmmeter to the two terminals of the sensor.
4. Using a calibrated thermometer, compare the resistance of the
sensor to the temperature of the water. Refer to the engine coolant
sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
6. If the sensor does not meet specification, it must be replaced.
Submerge the end of the coolant temperature sensor in
cold or hot water and check the resistance
Click to Enlarge
Coolant temperature sensor wiring diagram
Click to Enlarge
Coolant temperature sensor temperature vs. resistance
values
Click to Enlarge
1.
2.
3.
4.
Remove the ECT sensor from the vehicle.
Immerse the tip of the sensor in container of water.
Connect a digital ohmmeter to the two terminals of the sensor.
Using a calibrated thermometer, compare the resistance of the
sensor to the temperature of the water. Refer to the engine coolant
sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
6. If the sensor does not met specification shown in the temperature
versus resistance chart, it must be replaced.
7. The sensor may also be checked in the vehicle. Unplug the sensor
and attach a digital ohmmeter to the two terminals of the sensor.
8. Using a calibrated thermometer, compare the resistance of the
sensor to the ambient air temperature.
9. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
10. If the sensor does not met specification shown in the temperature
versus resistance chart, it must be replaced.
The ECT sensor is usually located near the thermostat
housing
Click to Enlarge
Using a thermometer, a DVOM and some jumper leads,
check the resistance of the ECT sensor and compare your
readings to those in the chart
Click to Enlarge
Submerge the end of the coolant temperature sensor in
cold or hot water and check the resistance
Click to Enlarge
Engine Coolant Temperature (ECT) sensor wiring
diagram
Click to Enlarge
Engine Coolant Temperature (ECT) sensor temperature
vs. resistance values
Click to Enlarge
1.
2.
3.
4.
Remove the ECT sensor from the vehicle.
Immerse the tip of the sensor in container of water.
Connect a digital ohmmeter to the two terminals of the sensor.
Using a calibrated thermometer, compare the resistance of the
sensor to the temperature of the water. Refer to the engine coolant
sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
6. If the sensor does not meet specification, it must be replaced.
Intake Air Temperature (IAT) and Engine Coolant
Temperature (ECT) sensor wiring diagram
Click to Enlarge
ECT sensor temperature vs. resistance values
Click to Enlarge
1.
2.
3.
4.
Remove the sensor from the vehicle.
Immerse the tip of the sensor in container of water.
Connect a digital ohmmeter to the two terminals of the sensor.
Using a calibrated thermometer, compare the resistance of the
sensor to the temperature of the water. Refer to the engine coolant
sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
6. If the sensor does not meet specification, it must be replaced.
Submerge the end of the coolant temperature sensor in
cold or hot water and check the resistance
Click to Enlarge
Coolant temperature sensor wiring diagram
Click to Enlarge
Coolant temperature sensor temperature vs. resistance
values
Click to Enlarge
1.
2.
3.
4.
Remove the ECT sensor from the vehicle.
Immerse the tip of the sensor in container of water.
Connect a digital ohmmeter to the two terminals of the sensor.
Using a calibrated thermometer, compare the resistance of the
sensor to the temperature of the water. Refer to the engine coolant
sensor temperature vs. resistance illustration.
5. Repeat the test at two other temperature points, heating or cooling
the water as necessary.
6. If the sensor does not met specification, it must be replaced.
Engine Coolant Temperature (ECT) sensor wiring
diagram
Click to Enlarge
Engine Coolant Temperature (ECT) sensor temperature
vs. resistance values
Click to Enlarge
PATH: Engine Cooling > Coolant Temperature Sensor > Removal & Installation
Removal & Installation
1. Disconnect the negative battery cable and drain the engine
coolant.
2. Disconnect the sensor electrical lead and unscrew the sensor.
To install:
3. Install the sensor and tighten it to 17 ft. lbs. (23 Nm). Connect the
electrical lead.
4. Connect the battery cable and fill the engine with coolant.
Coolant temperature and oil pressure senders-4.3L
engines
Click to Enlarge
Coolant temperature and oil pressure senders-5.0L and
5.7L engines
Click to Enlarge
Coolant temperature and oil pressure senders-7.4L
engines
Click to Enlarge
Coolant temperature and oil pressure senders-6.2L and
6.5L diesel engines
Click to Enlarge
1. Disconnect the negative battery cable.
2. Drain the cooling system below the level of the sensor and
disengage the sensor electrical connection.
3. Remove the coolant sensor.
To install:
4. Install the sensor and engage the electrical connector.
5. Refill the cooling system and connect the negative battery cable.
1. Disconnect the negative battery cable.
2. Drain the cooling system below the level of the sensor and
disengage the sensor electrical connection.
3.
To install:
4.
5.
1.
2.
Remove the coolant sensor.
Install the sensor and engage the electrical connector.
Refill the cooling system and connect the negative battery cable.
Disconnect the negative battery cable.
Drain the cooling system below the level of the sensor and
disengage the sensor electrical connection.
3. Remove the coolant sensor.
To install:
4. Install the sensor and engage the electrical connector.
5. Refill the cooling system and connect the negative battery cable.
1. Disconnect the negative battery cable.
2. Drain the cooling system below the level of the sensor and
disengage the sensor electrical connection.
3. Remove the coolant sensor.
To install:
1. Install the sensor and engage the electrical connector.
2. Refill the cooling system and connect the negative battery cable.
1. Disconnect the negative battery cable.
2. Drain the cooling system below the level of the sensor and
disengage the sensor electrical connection.
3. Remove the coolant sensor.
To install:
1. Install the sensor and engage the electrical connector.
2. Refill the cooling system and connect the negative battery cable.
PATH: Engine Cooling > Coolant Temperature Sensor > Operation
Operation
Animations and Tech Tips
Click to view: A typical CTS circuit
Click to view: A typical CTS circuit
Click to view: A temperature/resistance chart
About the coolant temperature sensor
The coolant temperature sender changes resistance as the coolant temperature
increases and decreases.
The coolant temperature sensor is a thermistor (a resistor which changes value
based on temperature). Low coolant temperatures produce high resistance
(100,000 ohms at -40°F/-40°C) while low temperatures causes low resistance
(70 ohms at 266°F/130°C). The sensor is mounted in the coolant stream and
the ECM supplies a 5 volt signal to the sensor through a resistor in the ECM
and measures the voltage. The voltage will be high when the engine is cold,
and low when the engine is hot. By measuring the voltage, the ECM knows the
engine coolant temperature.
Coolant temperature sensor location
Click to Enlarge
The Engine Coolant Temperature (ECT) sensor is mounted in the intake
manifold and sends engine temperature information to the ECM. The ECM
supplies 5 volts to the coolant temperature sensor circuit. The sensor is a
thermistor which changes internal resistance as temperature changes. When the
sensor is cold (internal resistance high), the ECM monitors a high signal
voltage which it interprets as a cold engine. As the sensor warms (internal
resistance low), the ECM monitors a low signal voltage which it interprets as
warm engine.
Engine Coolant Temperature (ECT) sensor location4.3L, 5.0L and 5.7L engines
Click to Enlarge
Engine Coolant Temperature (ECT) sensor location-7.4L
engines
Click to Enlarge
The Engine Coolant Temperature (ECT) sensor is mounted in the intake
manifold and sends engine temperature information to the ECM. The ECM
supplies 5 volts to the coolant temperature sensor circuit. The sensor is a
thermistor which changes internal resistance as temperature changes. When the
sensor is cold (internal resistance high), the ECM monitors a high signal
voltage which it interprets as a cold engine. As the sensor warms (internal
resistance low), the ECM monitors a low signal voltage which it interprets as
warm engine.
View of the Engine Coolant Temperature (ECT) sensor
Click to Enlarge
Engine Coolant Temperature (ECT) sensor location
Click to Enlarge
The coolant temperature sensor is a thermistor (a resistor which changes value
based on temperature). Low coolant temperatures produce high resistance
(100,000 ohms at -40°F/-40°C) while low temperatures causes low resistance
(70 ohms at 266°F/130°C). The sensor is mounted in the coolant stream and
the ECM supplies a 5 volt signal to the sensor through a resistor in the ECM
and measures the voltage. The voltage will be high when the engine is cold,
and low when the engine is hot. By measuring the voltage, the ECM knows the
engine coolant temperature effects most systems the ECM controls.
Coolant temperature sensor location
Click to Enlarge
The Engine Coolant Temperature (ECT) sensor is mounted in the intake
manifold and sends engine temperature information to the ECM. The ECM
supplies 5 volts to the coolant temperature sensor circuit. The sensor is a
thermistor which changes internal resistance as temperature changes. When the
sensor is cold (internal resistance high), the ECM monitors a high signal
voltage which it interprets as a cold engine. As the sensor warms (internal
resistance low), the ECM monitors a low signal voltage which it interprets as
warm engine.
Engine Coolant Temperature (ECT) sensor location—
4.3L, 5.0L and 5.7L engines
Click to Enlarge
Engine Coolant Temperature (ECT) sensor location—
7.4L engines
Click to Enlarge