How to Test Parking Sensors with a Multimeter (Guide)
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Parking sensors are position sensors that help the driver recognize nearby objects when the car is parked. They are usually installed on the bumpers of cars. By definition, these devices are classified as parking assist sensors.
However, sometimes problems with the parking sensor can occur, making driving difficult. Diagnosing these problems can be tricky, one of the easiest ways to figure out what's wrong is to use a multimeter.
Checking the parking assist sensor can be tricky. In this tutorial, you will learn how to use a multimeter to test parking sensors and what to look for if they are damaged.
How does the parking assist sensor work?
With the increase in the size of cars and the reduction of parking spaces, these sensors are becoming more common. There are two main types of sensors, depending on their location:
- Front bumper sensors
- Rear bumper sensors
These sensors work either on ultrasonic or electromagnetic principle. The rear parking sensors are activated and send out ultrasonic waves when the driver engages reverse gear. When these waves collide with a nearby object, they are reflected and picked up again by the sensors. The ECU determines the distance from the object to the vehicle based on the time elapsed between transmission and reacquisition of the waves. (1)
When the car approaches an object, the parking system warns the driver with an audible signal or a visual indicator. As the vehicle approaches an object, the volume of the horn increases, prompting the driver to stop abruptly.
In addition to these sensors, some car manufacturers use rear parking sensor cameras to provide a more accurate picture of the environment behind the vehicle. Reverse parking sensors are often built to provide updates at a considerable distance from other objects. (2)
Testing Parking Sensors with a Multimeter in 6 Steps
Vehicle parking sensors are a vital safety feature. The most effective approach to assessing their accuracy is to use a multimeter.
To achieve this goal:
- In this test, you will set up your multimeter to measure electrical resistance.
- Remove the parking sensor from the vehicle.
- Locate the three pin parking sensor (positive, signal, minus). The two most common types of parking sensors are three-pin (pink wire) and four-pin (ground right in the front bumper).
- The resistance of a good sensor between "plus" and "minus" should be more than 0.5 MΩ (the higher, the better).
- Between the "minus" and the signal contact (depending on the sensor) there must be a resistance of 2 - 40 kOhm.
- Between the signal contact and the "plus" there will be a resistance of about 2-40 kOhm.
When using the above troubleshooting equipment, there should be no open or short circuit in any of these connections. Otherwise, they will not work properly when re-placed in the car and may even put it in danger if they break when driving out of the garage.
Benefits of Parking Assist Sensors
Parking sensors have the following advantages:
- Reducing the blind spots surrounding the car makes the difficult process of parking in hard-to-reach places more accessible.
- When parking the car, this technique reduces driver fatigue.
A better understanding of the environment behind the vehicle reduces the chance of harm to the vehicle or its surroundings.
Ultrasonic and ultramagnetic parking sensor
| Ultrasonic parking sensor | Ultramagnetic parking sensor |
| Ultrasonic sensors produce ultrasonic waves that bounce off anything in their path. Four or six sensors are usually mounted on the bumper. When the sensor detects a reflection, it transmits information to its central unit. It determines how far away an object is based on the time difference between each wave arriving back at the sensor. This is common in most cars. These sensors do not require drilling. | Electromagnetic parking sensors are more relevant and reliable, but they are more expensive. Electromagnetic parking sensors are installed on the inside of the bumper. They are not as common as ultrasonic parking sensors. They are so unusual that most people have no idea what it means to see them on a car. Drilling is usually required for ultrasonic transducers. However, these sensors are rugged and designed to withstand harsh weather conditions. |
Take a look at some of our articles below.
- How to check an ABS sensor with a multimeter
- Multimeter resistance symbol
- How to test a three-wire crankshaft sensor with a multimeter
Recommendations
(1) electromagnetic principle – https://www.britannica.com/
science/electromagnetism
(2) environment - https://greatist.com/happiness/ways-help-environment
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