Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2000MALIBU V6-3.1L VIN JREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSCOOLANT TEMPERATURE SENSOR/SWITCH (FOR COMPUTER)DESCRIPTION AND OPERATION
2000 Chevrolet Malibu V6-3.1L VIN J
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
2000 Chevrolet Malibu V6-3.1L VIN JSECTION Description and Operation
The engine coolant temperature sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream.
Low coolant temperature produces a high resistance (100,000 ohms at -40°C/-40°F) while high temperature causes low resistance (70 ohm at 130°C/266°F).
The PCM supplies a 5.0 volt signal to the engine coolant temperature sensor through a resistor in the PGM 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 PCM calculates the engine coolant temperature. Engine coolant temperature affects most systems the PCM controls.
The scan tool displays engine coolant temperature in degrees. After engine startup, the temperature should rise steadily to about 90°C (194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and intake air temperature displays should be close to each other.
A hard fault in the engine coolant sensor circuit should set DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage, or DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage, an intermittent fault should set a DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage, or DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent
High Voltage.
The ECT sensor (3) also contains another circuit which is used to operate the engine coolant temperature gauge located in the instrument panel.
Low coolant temperature produces a high resistance (100,000 ohms at -40°C/-40°F) while high temperature causes low resistance (70 ohm at 130°C/266°F).
The PCM supplies a 5.0 volt signal to the engine coolant temperature sensor through a resistor in the PGM 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 PCM calculates the engine coolant temperature. Engine coolant temperature affects most systems the PCM controls.
The scan tool displays engine coolant temperature in degrees. After engine startup, the temperature should rise steadily to about 90°C (194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and intake air temperature displays should be close to each other.
A hard fault in the engine coolant sensor circuit should set DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage, or DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage, an intermittent fault should set a DTC P1114 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent Low Voltage, or DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent
High Voltage.
The ECT sensor (3) also contains another circuit which is used to operate the engine coolant temperature gauge located in the instrument panel.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.