The Ford Fusion MAP Sensor in your 2.5 liter 4 cylinder engine plays a huge role in your Ford’s EFI system. Otherwise known as the manifold absolute pressure sensor, this unit gives your Ford engine computer information about the incoming air charge. Using this data your engine computer can calculate the correct fuel injector duty cycle.
When your Fusion MAP Sensor begins to fail, it’s going to cause serious problems with your engine and how it operates. Today, I’ll be showing you how to test the Fusion MAP Sensor in a 2014 four cylinder Fusion SE.
In order to test your pressure sensor you will need to use a digital multimeter. If you are not sure what this device is, or even how to use one check out our guide here.
Although the Fusion MAP Sensor is a standard 3 pin unit, the one found in our 2014 has four pins to the engine harness connector. The is one pin that’s a blank on this Fusion engine harness. To begin you will be opening your Fusion hood and locating the pressure sensor, which is mounted to the intake manifold.
Because the 2.5 liter Ford engine exhaust faces rearward towards the firewall, you will need to look directly downward. You should notice the Fusion MAP Sensor mounted to the intake manifold runners.
We will begin by testing your manifold pressure sensor for power at the engine harness first.
Test your Fusion MAP Sensor for Power
Reach down and unplug your MAP sensor, but make sure to take extreme care here. Because the intake side of this engine is very close to your cooling fans, you are best done when the car is completely cold. Your cooling fans can turn on at any time, which can cause extreme damage to yourself or your multimeter.
If you are not comfortable working on your own Ford Fusion, stop now and take it to a professional mechanic. Make sure to check our safety guide if you are deciding to proceed with our Fusion MAP Sensor DIY guide.
Unplug the four pin MAP connector and you will be using your multimeter to test the front of the harness. Remember to gently touch your test probes to the front of the connector, never force the probes into the engine harness.
To test your Fusion MAP Sensor for power, you will need to test PIN 2 as shown in the wiring diagram below. PIN 3 is the empty wiring pin which doesn’t have any wires in it. Check this PIN 2 for 5 volts of DC power, and if you don’t have that here make sure that your Fusion key is turned to the “ON” position.
Again your cooling fans can turn on at any moment, so make sure your vehicle is completely cold and always be careful working around the front of your Fusion. Once you have confirmed that you have 5 volts of DC power here, you can check for the low reference ground signal.
The engine wiring ground signal is PIN 4, make sure you are not testing on the actual MAP sensor itself. Remember that you are testing at the engine harness, because if you send power to this ground wire you will fry your ECU.
There should be a negative ground signal at this wire from your engine computer. Once you know that your Fusion MAP Sensor has power and ground, you can now check for the signal.
Test your Fusion MAP Sensor for signal
Your intake pressure sensor should now be confirmed to have power and ground. This means that there’s just one test left for your Fusion MAP sensor, and that’s the signal wire. The signal wire you will need to test is PIN 1 and in order to test it you will need to remove your MAP sensor or reconnect it and test the wire itself.
Remove your pressure sensor and with the use of a hand pump you can test the signal being sent to your computer. This can be done with the use of a Mighty Vac or a vacuum pump at the inlet of your Fusion MAP sensor.
Now reconnect the the connector to your MAP sensor and measure the voltage out of PIN 1. With the MAP sensor completely disconnected you should see 0-0.3 volts of signal. At 15 hg of vacuum you should see around 2.3 volts of power. You can also test this by re-installing your MAP sensor and starting your engine.
Again because of the proximity of the cooling fans, make sure your hands, clothing and tools are free and safe. With the engine started at idle, the sensor should read between .8-1.0 volts of DC signal.
If any of these testing values are outside of these ranges, make sure to replace your Fusion MAP sensor right away. You can use a OBDII scan tool to clear and erase any stored DTC trouble codes.
