Testing your Nissan D21 pickup's MAF sensor, to see if it's bad or not, can be done in three easy and simple tests. They're all done with a multimeter, since you don't need an automotive scan tool to do it and this article will show you how.
This part of this test article includes some handy information that you'll need to make testing the MAF on your D21 as easy and as pain free as possible. This MAF test article covers the Nissan D21 Hard Body pickup (with a 2.4L 4 Cylinder) for the years: 1990, 1991, 1992, 1993, 1994, and 1995.
Contents of this tutorial:
You can find this tutorial in Spanish here: Prueba: Sensor de Flujo De Aire (MAF) 2.4L Nissan D21 Hard Body (1990-1995) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicle:
- Nissan D21 pickup 2.4L: 1990, 1991, 1992, 1993, 1994, 1995
NOTE: There are 4 other Nissan MAF sensor test articles:
- How To Test The Nissan MAF Sensor Frontier, Quest, Pathfinder, and Xterra 3.3L V6 (1999-2004).
- How To Test The Nissan MAF Sensor: Maxima 3.0L V6 (1995-1999).
- How To Test The Nissan MAF Sensor: Sentra 1.6L 4 cyl. (1995-1999).
- How To Test The Nissan MAF Sensor: Sentra 1.8L 4 cyl. (2000-2002).
Common Symptoms Of A Bad Nissan MAF Sensor
This list covers the majority of symptoms I've seen with this type of Nissan mass air flow sensor:
- MAF codes that light up the check engine light (CEL) on your instrument cluster.
- MAF sensor malfunction that DOES NOT light up the check engine light (CEL).
- Lean and/or Rich code(s).
- Fuel Trim code(s).
- A tremendous lack of power upon acceleration.
- Black smoke coming from the tail-pipe.
- Bad gas mileage.
- Vehicle may idle rough and stall.
What Tools Do I Need?
The most important tool that you're gonna' need is a digital multimeter (or an analog multimeter), this bad boy doesn't have to be an expensive one. A scan tool (automotive diagnostic scanner) is not needed. I would also recommend using a wire-piercing probe to to test the signal of each wire (to see what this tool looks like, click here: Wire-Piercing Probe.
Circuit Descriptions Of The Nissan MAF Sensor Connector
The mass air flow sensor on your Nissan D21 pickup has three wires attached to it. You'll notice that the photos (in the image viewer) have the MAF connectors lettered A thru' C (if you look closely at the MAF sensor itself on your D21 pickup, you'll see these letters on it too). I'll be using these letters for the circuit descriptions. Here's the description of each circuit below:
- Letter A:
- Power (12 Volts).
- Letter B:
- MAF Signal.
- Letter C:
- Ground.
I recommend using a wire-piercing probe to test the signals in the wires, since this method will be the most effective and easiest way of getting to the signal. If you need to see what this tool looks like, click here: Wire-Piercing Probe. Independent of the method you use, be careful not to damage the wire(s). Take all safety precautions.
How Does The D21 MAF Sensor Work?
The mass air flow (MAF) sensor's job is to measure the amount of air that the engine is breathing. And this measurement of the air flow is sent to the D21's fuel injection computer as an analog DC voltage signal.
To be a little more specific since D21's four cylinder engine will breathe in more air at, let's say, 2,500 RPMs than when it's sitting at an idle of 900 RPMs this will cause the MAF sensor to send a higher DC voltage signal to the computer than at idle. It's as simple as that!
When testing this DC voltage MAF signal, the important thing to know is not an actual Volts DC number at a specific RPM, but to look for crazy and extreme fluctuations in the MAF voltage signal that don't correspond to the actual air intake (RPMs) of the engine or NO SIGNAL AT ALL. In the TEST 3 section of this article, I'll show how you just how to test this so that you can confirm that your Nissan pickup's MAF sensor is bad or not.
TEST 1: Testing The MAF Sensor 12 Volts Circuit
The starting point, of your Nissan D21 pickup's diagnostic, is checking that it is receiving 10 to 12 Volts with the key on and engine off.
The wire that feeds battery power to the MAF sensor is the wire labeled with the letter A in the photo above.
NOTE: Void probing the front of the connector's female terminal for this voltage. The procedure I recommend for you to use (to accomplish all of the tests below) is to use a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.
Whatever method you use, the key here is not to damage the female terminal or the wire. Again, be careful. Use common sense and take all necessary safety precautions.
OK, let's get this show on the road:
- 1
Place your multimeter in Volts DC mode and disconnect the MAF sensor from its electrical connector.
- 2
Probe the MAF sensor wire, that's identified with the letter A in the photo, with the red multimeter test lead.
- 3
Connect the black lead of the multimeter to the battery negative (-) terminal.
- 4
Turn the key to the ON position but don't crank or start the engine.
- 5
Your multimeter should display 10 to 12 Volts DC if the MAF sensor is getting power.
Let's analyze your test results:
CASE 1: Your multimeter registered 10 to 12 Volts. This result indicates that the D21's MAF sensor is getting juice (power).
The next step is to test the Ground circuit, go to: TEST 2: Testing The MAF Sensor Ground Circuit.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Recheck all of your multimeter connections and retest. If still no voltage, then this result exonerates the D21's MAF sensor as the cause of the MAF code or MAF issue, since without this voltage, the MAF sensor will not produce a signal to the computer.
Finding and repairing the source of this missing voltage will resolve the MAF sensor issue with your Nissan D21 pickup.
