The manifold absolute pressure sensor or MAP sensor of the car measures the pressure of the air entering the intake manifold of the engine and then sends the recorded reading to the electronic control unit (ECU) of the car.
This computer then calculates the amount of fuel that ought to be fed into the combustion chamber for the complete combustion of the fuel.
Failure of the MAP sensor of the car can have very adverse effects on the health of the car engine. Here is a guide on how to test the MAP sensor of the car with or without the digital multimeter or DMM. In this powerful step-by-step guide, you will learn how to test MAP sensors with and without a multimeter.
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How To Test MAP Sensor
There are mainly three wires in the MAP sensor of the car namely the Ground wire, Signal wire, and Power wire. But some MAP sensors have an extra fourth signal wire for the intake air temperature sensor.
The proper working of all these three wires is mandatory, therefore, it is important to test all these wires one by one, if the sensor loses its job.
How To Test MAP Sensor With Multimeter
1. The MAP Sensor’s Power Wire Test
- Set the multimeter to the voltmeter settings.
- Turn the ignition switch ON.
- Connect the red lead of the multimeter to the power (Hot) wire of the MAP sensor.
- Connect the black lead of the multimeter to the ground terminal of the battery.
- The voltage shown should be around 5 volts.
2. The MAP Sensor’s Ground Wire Test
- Keep the ignition switch turned ON.
- Turn the multimeter to the continuity tester.
- Connect both leads of the digital multimeter together.
- At connecting both leads, you should hear a beep sound because of continuity.
- Then, you have to plug in the red lead of the multimeter in the ground wire of the MAP sensor.
- Connect the black lead of the multimeter to the ground terminal of the battery.
- If you hear a beep sound that should confirm the continuity, hence proving that your ground wire is working properly.
3. The MAP Sensor’s Signal Wire Test
- Turn the ignition switch ON.
- Set the digital multimeter to the voltmeter settings.
- Connect the red lead of the multimeter to the signal wire.
- Connect the black lead of the multimeter to the ground.
- With the ignition switch ON and engine OFF, the signal wire would show the reading around 5 volts, it is because there is no air pressure.
- With switching the engine on, the multimeter would show around 1-2 volts if the signal wire is working properly. It is because air starts to flow inside the intake manifold and changes the value of the signal wire.
4. The MAP Sensor’s IAT Wire Test
- Turn the multimeter to the voltmeter settings.
- Turn the ignition switch ON.
- Attach the red lead of the multimeter to the signal wire of the intake air temperature sensor.
- Attach the black lead of the multimeter to the ground.
- At 36 degrees Celcius temperature of the air, the IAT sensor reading should be around 1.6 volts.
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How To Test MAP Sensor Without Multimeter
In case you do not have a digital multimeter, you can also use a scan tool to test the MAP sensor of the car. Here is a guide on how to test the MAP sensor with a scan tool.
Check The Reading Of The MAP Sensor At Idle
- Switch on the ignition switch of the car. At idle the MAP sensor of the car should read the air pressure in the surroundings.
- If the MAP sensor reads the same or a close reading as the barometric sensor readings, the MAP sensor is working properly in idle conditions.
Check The Reading Of The MAP Sensor While Working
- Switch on the engine of the car, the MAP sensor will take a reading.
- Press the car’s throttle and notice the MAP sensor’s reading.
- When the throttle has been pressed the reading of the MAP sensor should rise sharply and go down as soon as the throttle of the car is released.
- The reading of the MAP sensor should go more down as compared to when the throttle was not pressed.
- If this happens the MAP sensor is working properly.
Making A Graph Of The Reading Of The MAP Sensor
Lastly, make a graph of the reading shown by the MAP sensor on the scan tool. If the readings of the graph are considerably variable, you should consult an expert as this could be a sign of a failing MAP sensor.
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Frequently Asked Questions (FAQs)
A MAP sensor can be tested with a multimeter to see if it is functioning properly. The procedure is described above. If the sensor is not working, the engine will not run correctly and may stall.
A MAP sensor is a type of sensor that measures the pressure inside an engine, specifically the amount of vacuum. This reading is important because it helps the engine control its air/fuel mixture. The ideal reading for a MAP sensor, at idle, is 1 to 2 volts. This reading indicates that there is a strong vacuum present and that the engine is operating correctly. If the reading is outside of this range, it could indicate a problem with the engine.
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