The mass air flow (MAF) sensor, on your 2.5L 6 cylinder Suzuki Grand Vitara (or 2.5L Chevrolet Tracker), can be tested with a multimeter.
You don't need a scan tool for the MAF sensor test and in this tutorial I'll show you how to test it in a step-by-step way.
Tutorial contents at a quick glance:
- Symptoms Of A BAD MAF Sensor.
- TEST 1: Checking The MAF Sensor Signal.
- TEST 2: Verifying The MAF Is Getting Power.
- TEST 3: Verifying The MAF Is Getting Ground.
- MAF Sensor Code Keeps Coming Back.
Symptoms Of A BAD MAF Sensor
To calculate the correct amount of fuel to inject into the engine, your Suzuki's PCM needs to know the amount of air entering into the engine.
This is where the mass air flow (MAF) sensor's role of measuring the air the engine breathes comes into play.
Since the MAF sensor is such a crucial component of your Grand Vitara's engine management system... when it fails it wreaks havoc on your engine's performance.
Here's a list of the symptoms you'll see with a failed MAF sensor:
- Diagnostic trouble codes (DTCs):
- P0101: MAF Sensor Performance.
- P0102: MAF Sensor (MAF) Low Input.
- P0103: MAF Sensor (MAF) High Input.
- Doesn't pass the smog check.
- Engine idles rough.
- Engine takes forever to start (extended cranking time).
- Engine doesn't start.
- Black smoke coming out of the tail-pipe as engine runs.
Let's jump into the first test in the next subheading...
TEST 1: Checking The MAF Sensor Signal
The signal that the mass air flow (MAF) sensor creates is a voltage signal that you and I can measure with a multimeter.
This voltage signal is a direct reaction to the amount of air passing by the MAF sensor's hot wires. To be more specific: The MAF signal voltage increases the more air enters the throttle body (for example when you step on the accelerator pedal).
As you let go off the accelerator pedal and less air enters the throttle body... the MAF sensor's signal voltage starts to decrease.
With a multimeter, tapped into the MAF signal wire, we can observe theses voltage changes. The wire that carries this signal is the violet with white stripe (VIO/WHT) wire of the 3-wire MAF sensor connector.
NOTE: Be careful and take all necessary safety precautions! The MAF test in this section is done with your Suzuki Grand Vitara's engine running.
NOTE: The connector in the illustration above is the connector on the MAF sensor itself and NOT the engine wiring harness MAF connector.
These are the test steps:
Set the multimeter to Volts DC mode and probe the VIO/WHT wire of the MAF sensor connector with the red multimeter lead.
The VIO/WHT wire is the one that connects to MAF sensor pin 1 in the illustration above.
NOTE: You'll need to use a tool like a wire piercing probe to access the signal inside the wire. To see what a wire piercing probe looks like, go here: Wire Piercing Probe.
Ground the BLACK multimeter test lead directly on the battery negative terminal.
Have a helper start the engine. Wait for the engine's idle to stabilize and observe your multimeter's voltage reading.
With the engine idling, the voltage reading should be about 1.5 to 1.8 Volts DC.
Now, have your helper accelerate the engine. The voltage should increase.
At around 4,000 RPMs, the multimeter should register to about 3 Volts DC.
Decelerate and accelerate the engine several times as you observe the multimeter
Your multimeter should register a decrease/increase in voltage as you decelerate/accelerate the engine if the MAF sensor is good.
If the MAF sensor is bad, the voltage will be stuck at a certain number no matter how much you accelerate/decelerate the engine.
OK, let's take a look at what your MAF sensor test results mean:
CASE 1: The MAF sensor produced and increasing/decreasing voltage signal as you accelerated/decelerated the engine: This tells you that the mass air flow sensor is OK (not defective).
CASE 2: Your multimeter registered voltage, but it did not increase or decrease as you accelerated/decelerated the engine: This confirms that the mass air flow (MAF) sensor on your 2.5L Grand Vitara (or 2.5L Chevrolet Tracker) is BAD. Replacing the MAF sensor will solve the MAF sensor trouble code lighting up the check engine light.
CASE 3: Your multimeter registered 0 Volts: This usually means that the MAF sensor is fried. To be absolutely sure, I suggest confirming that the MAF sensor has power and ground. If both (power and ground) are present, the MAF sensor is BAD. To test for power, go to TEST 2: Verifying The MAF Sensor Is Getting Power.