TEST 1: Making Sure The MAF Sensor Is Getting Power
 
The very first thing that we'll do is check that the MAF sensor is receiving power.
The wire labeled with the #3 (in the photo above) is the one that provides power to the MAF sensor.
These are the test steps:
- 1Put the multimeter in Volts DC mode and disconnect the MAF sensor from its electrical connector. 
- 2Probe the wire labeled with the #3 with the red multimeter test lead and using an appropriate tool. 
- 3Connect the black multimeter probe to the battery negative (-) post. 
- 4Turn the key ON but don't crank or start the engine. 
- 5The multimeter should read 10 to 12 Volts DC if power is available. 
Let's interpret your test result:
CASE 1: Your multimeter registered 10 to 12 Volts DC. This is the correct and expected test result.
Your next step is to go to: TEST 2: Making Sure The MAF Sensor Is Getting Ground.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts DC. This test result tells you that the MAF sensor is not getting power. Without power, it will not function.
Your next step is to find out why these 10 to 12 Volts are missing and restore them.
TEST 2: Making Sure The MAF Sensor Is Getting Ground
 
Now that you have confirmed that your Volvo's MAF sensor is getting power, the next step is to make sure it's getting chassis Ground.
The wire labeled with the #1 (in the photo above) is the one that provides Ground to the MAF sensor.
We'll do a simple multimeter voltage test to confirm the presence of Ground.
These are the test steps:
- 1Place your multimeter in Volts DC mode and turn the key to its OFF position. 
- 2Probe the wire labeled with the #1 with the black multimeter test lead and using an appropriate tool. 
- 3Connect the red multimeter probe to the battery positive (+) post. 
- 4The multimeter should read 10 to 12 Volts DC if chassis Ground is available. 
Let's interpret your test result:
CASE 1: Your multimeter registered 10 to 12 Volts DC. This is the correct and expected test result.
Your next step is to go to: TEST 3: Testing The 2nd Ground Circuit.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts DC. This test result tells you that the MAF sensor is not getting Ground. Without Ground, it will not function.
Your next step is to find out why Ground is missing and restore it.
