Last Updated on October 22, 2023 by Kevin Chen
Image source Your mechanic
As a key electronic component in a vehicle, the main function of a throttle position sensor (TPS) is to monitor the exact position of the throttle valve for the optimum performance. A well-positioned throttle valve will ensure that the engine performs well when required.
Knowing the relevance of a throttle position sensor, it is always wise to ensure that it is in a perfect condition. And one way is by testing it. From the tests, you will be able to diagnose any possible problems and correct them in good time.
In this article, we are going to get into the deep details of testing a throttle position sensor.
Where is the throttle position sensor located?
The exact location of a TPS will vary depending on the model and make of the vehicle. In most vehicle’s, a throttle position sensor is found on the throttle body, which on the other hand is on the intake manifold.You will find a TPS at the top of the engine whereby it is directly connected to the accelerator pedal through a cable.
In other vehicles, the throttle position sensor is embedded right at the throttle pedal assembly. You should refer to your vehicle’s manufacturer manual for clarification about the exact position of the throttle sensor.
Test throttle position sensor using a multimeter
A multimeter remains an ideal tool for testing electronic components in a vehicle. You will need it to test the TPS.
This is because the most important test to do is the voltage and resistance test. Here are the steps and procedures that you should follow when testing a TPS.
Step 1: Inspect for the carbon build-up
Before you even begin to test the electronic parameters of a throttle position sensor, start by checking any possibilities of a carbon build-up.
Open the hood so that you can access the cleaning assembly From there, you can inspect for any impurities that might have accumulated on the throttle position sensor. Check out the accumulation of carbon and other impurities on the body walls and even throttle plate.
You can use a clean rag or a throttle cleaner to rub off these impurities until they are spotless.
Take note that accumulation of carbon on the TPS is likely to impair its proper functioning. And given its positioning, there is a high likelihood that it will be exposed to a significant amount of carbon material due to the burning of the fuel.
Step 2: Disconnect the TPS from the ground wire
If your throttle position sensor is connected to the ground wire, you should proceed to disconnect it. You can then inspect that connection point for any faults before cleaning it.
Proceed to set the digital multimeter to 15 volts or 20 volts then turn your car’s ignition ON. Position but don’t crank up the engine.
Place the positive (red) probe of the multimeter on the positive terminal of the car’s battery. Position the black (negative) probe of the multimeter on each of the TPS terminals.
Do this continuously until the multimeter indicates 12 volts. Now that is the ground terminal of the throttle position sensor and it also means that it has passed the test.
If after repeating placing the negative probe on the TPS tabs you don’t get the 12 volts, it means that the TPS is not grounded properly and needs to be fixed.
Once you establish that the ground is in perfect condition, you can proceed to the next steps of testing throttle position sensor.
Step 3: Finding the reference voltage terminal
This step entails finding the reference voltage terminal of a throttle position sensor. This is the part of a sensor that receives the voltage signal from the vehicle’s central control module (ECM). It ensure that the sensor work correctly and accurately.
A throttle position sensor has three terminals, the ground terminal, the reference voltage terminal and the signal voltage terminal.
To find and test this terminal, ensure that the car’s ignition still remains at the ON position without cranking up the engine.
Set the multimeter to the 10 volts and connect the black probe to the ground TPS terminal that we have located in the previous step. Since we have two remaining unknown TPS terminals, place the red probe in either of the terminals.
Observe the reading on the multimeter.
The TPS terminal that will result in the 5 volts reading is the reference voltage terminal.
However, if the multimeter does not give the 5V reading on any of the two terminals, chances are there could be a problem with the terminals or the circuit. Maybe you should check out for the loose wiring or signs of corrosion on the terminals.
At this point, we are left with one terminal to test: Signal voltage terminal.
Step 4: Testing the Signal Voltage Terminal
A signal voltage terminal of a throttle position sensor is designed to relay the voltage signals from the sensors to the electronic control module (ECM) of the vehicle. This signal is generated when the sensor monitors data about the engine and fuel injection.
This is the most important part of the testing process as it will determine the accuracy and reliability of the throttle position sensor. The results from this terminal will tell you whether the throttle position sensor can read the plate accurately when fully opened or closed.
To do this test, you will have to set the multimeter to the 10 DC volts then proceed to position the black probe to the ground terminal of the TPS just like in the previous step. Place the red probe on the signal voltage terminal of the TPS.
If this terminal is working, the multimeter should record a reading of between 0.2V to 1.5 volts. The range may be due to the fact that different TPS have different power range, a figure that is recorded by the signal voltage terminal.
If the multimeter records 0 volts, don’t panic, you can still proceed to the next step of testing.
While the multimeter is still intact, slowly but carefully open the throttle plate and observe the changes on the multimeter reading. The numbers should steadily increase as you continue opening. The value should stagnate between 3.5 volts to 5 volts when the plate is fully open.
However, you will need to change the whole throttle position sensor if you observe the following behavior on the multimeter reading:
- The readings skip by big margins even when you are opening the sensor’s plate slowly.
- The reading does not reach 5 volts when the plate is fully open
- The reading remain stagnant for long even as you open the plate gradually
- A little tap on the sensor causes significant changes on the multimeter reading
However, you should ignore the above red flags if you are using adjustable throttle sensor-like those found on most old vehicles.
Signs of a faulty TPS
Beyond the above steps, how can I tell that my throttle position sensor is faulty? Here are the symptoms that you should pay attention to.
-Rough acceleration: There is a direct relationship between the vehicle’s throttle and the acceleration. If the sensor is in a perfect working condition, you will be able to enjoy a smooth acceleration. On the other hand, a faulty TPS can cause acceleration problems. For example, the car may accelerate by itself even when you have not stepped on the pedal.
-Vibration when idling: A faulty throttle position sensor can cause the vehicle to vibrate constantly whenever the car is idling. You are likely to experience the same when driving slowly. The engine becomes unstable.
-Abnormal energy consumption: Are you experiencing getting low mileage from your car? Chances are your throttle position sensor is faulty. Different car components that are connected to the fuel injection system may overwork to compensate for this fault, leading to high consumption.
-Warning lights: Thanks to the modern technology, you can get real-time warning about the state of your vehicle’s throttle position sensor. The check engine may illuminate and if all other components are in good condition, the TPS could be the source of the problem.
To avoid all these troubles, it will be good to inspect your TPS regularly.
Next time you experience a problem with your car’s throttle system, it will be wise to check if the problem is with the TPS. You will be surprised by how much you will be able to save by choosing not to rush to the mechanic for a problem that you can easily work on and find the perfect solution.
Just follow the steps above and you will end up with a workable solution for your vehicle.
Consult your vehicle’s manual when executing each of the above steps and even when handling the throttle sensor. This will prevent causing costly damages.
Of course you should have the right tools and accessories for doing the tests.
However, if you are not fully confident in handling matters related to electricity, it will smart to consult experts in the field. A professional automotive mechanic will come in handy.
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