TEST 2: Making Sure The MAF Sensor Is Getting Ground
Once you've confirmed that your Toyota Camry's MAF sensor is receiving power, the next step is to check if it's getting Ground.
Ground is supplied to the MAF sensor through the brown (BRN) wire, which is labeled as wire number 5 in the photo above.
To test for Ground, we'll use a multimeter to safely verify its presence on the BRN wire.
IMPORTANT: The BRN wire connects directly to the fuel injection computer, so avoid applying 12 Volts (from the battery) to it —this can damage the computer. The multimeter voltage test described here is a safe and reliable way to check for Ground.
These are the test steps:
- 1
Disconnect the MAF sensor from its electrical connector.
- 2
Place your multimeter in Volts DC mode.
- 3
Turn the key ON but don't crank or start the engine.
- 4
Connect the red multimeter probe to the battery positive (+) post.
- 5
Probe the female terminal that connects to the wire labeled with the number 5 with the black multimeter test lead
The female terminal should connect to the BRN wire. - 6
The multimeter should read 10 to 12 Volts DC.
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 MAF Signal With A Multimeter.
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 this Ground is missing and restore it.
TEST 3: Testing The MAF Signal With A Multimeter
In this final test section, you'll measure the MAF signal that's sent from the sensor to the fuel injection computer.
The MAF signal is carried by the yellow with blue stripe (YEL/BLU) wire, labeled as wire number 6 in the photo above.
Here's what you're looking for:
- The MAF signal voltage should decrease as the engine accelerates.
- The MAF signal voltage should increase as the engine decelerates.
If the signal remains stuck at one value regardless of engine speed, it's a clear indication that the vane air flow sensor is defective.
NOTE: To perform this test, the vane air flow sensor must remain connected to its harness. You'll need to access the MAF signal using a back-probe or a wire-piercing probe. If you're unfamiliar with wire-piercing probes, you can check out an example (and where to buy it) here: Wire Piercing Probe
OK, let's get started:
- 1
Reconnect the MAF sensor to its 7-wire connector.
- 2
Place your multimeter in Volts DC mode.
- 3
Connect the black multimeter probe to the battery negative (-) post.
- 4
Connect the red multimeter test lead to the the wire labeled with the number 6 (see photo above)
This wire should be the the YEL/BLU wire of the connector. - 5
Start the engine and let it idle for about 5 minutes till it reaches its normal operating temperature.
- 6
Accelerate and decelerate the engine as you watch the multimeter's Volts DC readings.
- 7
The voltage reading should decrease when you accelerate the engine and increase when you decelerate the engine.
Idle RPM: 2.3 to 3.8 Volts DC.
3,000 RPM: 1.0 to 2.0 Volts DC.
Let's interpret your test result:
CASE 1: The voltage readings decreased and increased as indicated. This is the correct and expected test result and tells you that the vane air flow sensor (on your Toyota Camry) is working correctly.
CASE 1: The voltage readings DID NOT decrease or increase as indicated. This test result tells you that the vane air flow meter on your Toyota Camry is defective and needs to be replaced.
More 3.0L Toyota Camry Tutorials
You can find a complete list of 3.0L Toyota Camry tutorials in this index:
Here's a sample of the tutorials you'll find there:
- How To Test Engine Compression (1992-2006 3.0L V6 Toyota Camry).
- How To Test For A Blown Head Gasket (1992-2006 3.0L V6 Toyota Camry).
- How To Test The TPS (1997-2001 3.0L V6 Toyota Camry).
- How To Test The MAF Sensor (1997-2001 3.0L V6 Toyota Camry).
If this info saved the day, buy me a beer!
