See Figures 1, 2 and 3
The engine coolant temperature sensor is a variable resistor with a range of -40°F-265°F (-5°C-129°C).
The engine coolant temperature sensor provides an input voltage to the PCM. As the coolant temperature varies, the sensor resistance changes resulting in a different input voltage to the PCM.
When the engine is cold, the PCM will demand slightly richer air/fuel mixtures and higher idle speeds until normal operating temperatures are reached.
The engine coolant temperature sensor is also utilized for control of the cooling fan.
See Figures 4, 5 and 6
- Turn the ignition switch to the OFF position.
- Detach the coolant temperature sensor electrical connector.
- Using a DVOM set to the ohms scale, connect one lead to terminal A and the other lead to terminal B of the coolant temperature sensor connector.
- With the engine at normal operating temperature, approximaterly 200°F (93°C), the ohmmeter should read approximately 700-1000 ohms.
- With the engine at room temperature, approximately 70°F (21°C), the ohmmeter should read approximately 7000-13,000 ohms.
- If not within specifications, replace the engine coolant temperature sensor.
- Test the resistance of the wiring harness between PCM terminal 26 and the sensor wiring harness connector. Also check for continuity between PCM connector terminal 43 and the sensor wiring harness connector. If the resistance measures greater than 1 ohm, repair the wiring harness as necessary.
REMOVAL & INSTALLATION
See Figures 1, 2 and 3
On the 2.4L engine, the coolant temperature sensor threads into the top of the thermostat housing. On the 3.0L, 3.3L and 3.8L engines, the coolant temperature sensor is installed next to the thermostat housing.
- Locate the engine coolant temperature sensor on the engine.
- Disconnect the negative battery cable.
- Drain the engine coolant below the level of the sensor.
- Disconnect the sensor electrical harness.
- Using a deep-well socket or wrench, loosen and remove the sensor from the engine.
New coolant temperature sensors come with sealant already applied to the threads.
- Install the sensor in the vehicle and tighten securely. Tighten the sensor to 60 inch lbs. (7 Nm).
- Attach the electrical connector to the sensor.
- Refill the cooling system.
- Connect the negative battery cable.
- Start the engine, allow it to reach operating temperature and check for leaks.
- Check for proper sensor operation.