Throttle position sensor

Throttle Position Sensors - TPS

The throttle system in cars monitors and controls the flow of fluid in the engine. The vehicle's engine power can be controlled by changing the air-fuel ratio of the engine, which is done by throttle valve constraints. Modern cars operate on a drive-by-wire system. Here, in this system, sensors have replaced many mechanical systems in cars. A computerised unit called the Engine Control Unit monitors data derived from various sensors and controls the car. One of these automotive sensors is the throttle position sensor.

What is a throttle position sensor?

In cars, engine speed can be controlled by varying the amount of fuel and air supplied to the engine. In the past, a mechanical linkage was attached to the accelerator pedal to control the throttle butterfly valve. When the driver hit the throttle cable, the valve would open wide, causing a large flow of fuel or air, thus increasing the speed of the vehicle.

In modern cars, the throttle position sensor is used for this process. This sensor is used to monitor throttle valve position in vehicles. It can also be seen as a potentiometer that provides variable resistance depending on the throttle valve position.

Operating principle

This sensor is usually mounted on the valve body. It senses the position of the throttle valve or butterfly valve and transmits the information to the engine control unit. This sensor monitors how hard the accelerometer pedal is depressed and provides the output current that determines the pedal position. Pedal position controls the engine's airflow. If the valve is wide open, more air is supplied to the engine and vice versa. The output from this sensor, along with other sensors, is passed to the engine control unit, which decides how much fuel to inject into the engine.
This sensor is a three-wire potentiometer. Through the first wire, 5V power is supplied to the resistive layer of the sensors. The second wire is used as ground, while the third wire is connected to the potentiometer wiper and provides input to the motor control system.
Based on its construction, there are three types of throttle position sensors. These are throttle position sensors with built-in end switches, also known as Closed throttle position sensor, potentiometer type and combination of both types.

Applications

The sensor provides the engine control unit with information about the position of the butterfly valve. It is used to detect the idle position, the wide open throttle state of the valve. When the valve is in the idle state, the sensor output voltage is below 0.7V. When the full load condition is detected, the sensor output voltage is about 4.5V.
Damage to the throttle position sensor causes the Check Engine signal to flash. When this sensor is faulty, the computer could not correctly determine the valve position, which leads to overvoltage or vehicle stalling.