Testing the MAP sensor (and the resulting P0105 code) on your Nissan Pathfinder isn't hard and in this tutorial I'll show you how to.
You don't need any expensive testing equipment. You don't even need a scan tool. All you need is a multimeter.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (3.3L Nissan Pathfinder) (at: autotecnico-online.com).
MAP Sensor Circuit Descriptions
As you're already aware, the MAP sensor on your Nissan Pathfinder has 3 wires coming out of its harness connector.
These wires (circuits) are tasked with feeding power and Ground and taking the MAP signal back to the PCM.
All of the tests in this tutorial are done to the harness connector. In the image viewer you'll see the pin outs for the MAP sensor itself and its harness connector.
|Nissan Pathfinder MAP Sensor Pin Out|
|2||MAP Sensor Signal|
|3||5 Volt Reference|
Before You Start The MAP Sensor Test
Before you start the MAP sensor test on your Nissan Pathfinder (Frontier or QX4), you need to make sure that the sensor is getting vacuum (after the engine has started).
If the MAP sensor is not getting vacuum then the most likely culprit is the MAP/BARO switch solenoid valve that is defective (since this solenoid valve is the one that provides the MAP sensor with vacuum) or misrouted vacuum hoses.
For more information take a look at the following tutorial:
Where To Buy The MAP Sensor And Save
The MAP sensor on your Nissan Pathfinder (Frontier, QX4) isn't cheap. So if the MAP tests confirm that it's bad and you need to replace it then take a look at the following links and do some comparison shopping:
TEST 1: Checking For The MAP Sensor Signal
In this first test we're going to tap into the middle wire of the MAP sensor with a multimeter and see if the MAP sensor is producing a map signal when we manually apply vacuum to it.
You can apply vacuum to the MAP sensor with a vacuum pump or you can use the good ole' lungs (although using a vacuum pump is the most accurate way of testing the MAP sensor).
NOTE: Although you'll be bench testing the MAP sensor of your Nissan Pathfinder, you still need to leave the MAP sensor connected to its harness connector so that it can get both power and Ground (to produce a signal).
OK, these are the test steps:
Remove the MAP sensor from its location near the air filter box (if you need to gain access to its vacuum port).
Once you have removed it, reconnect it back to its harness connector.
Select Volts DC on your multimeter and probe the middle wire of the MAP sensor with the red multimeter test lead.
This is the wire that connects to the MAP sensor engine harness connector's terminal labeled with the number 2 in the image viewer.
The best way to get to the signal inside the wire is using a wire piercing probe (to see what this tool looks like, click here: Wire-Piercing Probe).
Ground the black multimeter test lead on the battery negative (-) terminal.
Now, connect your vacuum pump to the MAP sensor and turn the key to the ON position (don't start the engine).
With the key On and no vacuum applied to the MAP sensor your multimeter should display:
3.2 to 4.8V (this is no vacuum applied to the MAP sensor).
Apply Vacuum to the MAP sensor.
As you apply vacuum, your multimeter's voltage reading should start to decrease.
Once you have reached 7.8 in. Hg vacuum, your multimeter should read: 1.0 - 1.4 Volts DC.
NOTE: What you're looking for, as you apply and release vacuum is for the multimeter to show a decrease in voltage (as you apply vacuum) and an increase in the voltage back to 4.5+ Volts (as you release vacuum).
Let's take a look at what your test results mean:
CASE 1: The MAP sensor's voltage decreased as you applied vacuum- This tells you that the MAP sensor is OK and not the true cause of the MAP sensor codes.
This also confirms that your Nissan Pathfinder's (Frontier, QX4) MAP sensor is getting power (5 Volts) on wire and Ground.
CASE 2: The MAP sensor's voltage DID NOT decrease as you applied vacuum- This usually means that the MAP sensor is bad but we'll need to make sure that the MAP sensor is getting both power and Ground.
For this test, go to: TEST 2: Checking That The MAP Sensor Is Getting Power.