3 Wire Coolant Temperature Sensor Wiring Diagram

When it comes to engine performance, one of the important parameters that need to be monitored is the coolant temperature. The coolant temperature sensor is responsible for measuring the temperature of the coolant and sending the signal to the engine control module (ECM). In this article, we will discuss the wiring diagram of the 3 wire coolant temperature sensor which is commonly used in many vehicles today.

What is the 3 Wire Coolant Temperature Sensor?

The 3 wire coolant temperature sensor is a type of sensor that is used to measure the temperature of the engine coolant. It has three wires that are used for power, ground, and signal. The power wire is responsible for supplying power to the sensor, the ground wire is used to ground the sensor, and the signal wire is used to send the temperature signal to the ECM.

The 3 wire coolant temperature sensor is different from the 2 wire coolant temperature sensor which only has a power and ground wire. The 2 wire sensor is usually used in older vehicles while the 3 wire sensor is commonly used in newer vehicles.

Wiring Diagram of the 3 Wire Coolant Temperature Sensor

The wiring diagram of the 3 wire coolant temperature sensor consists of three wires: power, ground, and signal. The power wire is connected to an ignition-controlled power source, usually a fuse or a relay. The ground wire is connected to a good ground source, usually the engine block or the chassis. The signal wire is connected to the signal input of the ECM.

Wire Color Function Wire Gauge
Brown Power 16 gauge
Black Ground 16 gauge
Green Signal 20 gauge

The power wire should be connected to a fuse or a relay that is controlled by the ignition switch. This ensures that the sensor only gets power when the ignition is turned on. The ground wire should be connected to a good ground source such as the engine block or the chassis. The signal wire should be connected to the signal input of the ECM which is usually labeled as “ECT” or “Engine Coolant Temperature”.

FAQ

Q: What happens if the coolant temperature sensor fails?

A: If the coolant temperature sensor fails, it can cause several issues such as poor fuel economy, rough idling, and increased emissions. It can also cause the engine to run too hot or too cold which can lead to engine damage.

Q: How do I test the coolant temperature sensor?

A: To test the coolant temperature sensor, you can use a multimeter to check the resistance between the sensor’s signal wire and ground. You can refer to the vehicle’s service manual for the correct resistance values at different temperatures. If the resistance values are not within the specified range, the sensor may be faulty and needs to be replaced.

Q: Can I replace the 3 wire coolant temperature sensor with a 2 wire coolant temperature sensor?

A: No, you cannot replace the 3 wire coolant temperature sensor with a 2 wire coolant temperature sensor. The 2 wire sensor only has a power and ground wire and does not send a signal to the ECM. If you replace the 3 wire sensor with a 2 wire sensor, the ECM will not be able to monitor the engine coolant temperature.

Q: Can a faulty coolant temperature sensor cause the check engine light to come on?

A: Yes, a faulty coolant temperature sensor can cause the check engine light to come on. The ECM relies on the signal from the coolant temperature sensor to adjust the engine’s fuel mixture and ignition timing. If the sensor is faulty, it can cause the ECM to set a fault code and turn on the check engine light.

Q: How often should I replace the coolant temperature sensor?

A: The coolant temperature sensor should be replaced if it fails or if it is more than 10 years old. It is recommended to replace the sensor during routine maintenance to ensure proper engine performance and reliability.

In conclusion, the 3 wire coolant temperature sensor is an important component of the engine management system. It is responsible for measuring the temperature of the coolant and sending the signal to the ECM. Understanding the wiring diagram of the 3 wire coolant temperature sensor is essential for diagnosing and repairing any issues related to the coolant temperature.