TEST 2: Making Sure The MAF Sensor Is Getting Ground (1)
The MAF sensor gets Ground from two different wires:
- Ground 1: Brown (BRN) wire labeled with the number 4.
- Ground 2: Red with black stripe (RED/BLK) wire labeled with the number 5.
In this test section, we'll check that the brown (BRN) wire is delivering Ground.
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: Making Sure The MAF Sensor Is Getting Ground (2).
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: Making Sure The MAF Sensor Is Getting Ground (2)
So far, you have:
- Confirmed the BLK/ORG wire is delivering power (TEST 1).
- Confirmed the BRN wire is delivering Ground (TEST 2).
In this test section, we'll check that the red with black stripe (RED/BLK) wire is delivering Ground to the hot-wire element of the MAF sensor.
To test for this Ground on the RED/BLK wire, we'll use a multimeter to do a simple voltage test on it.
IMPORTANT: The RED/BLK 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 RED/BLK 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 4: 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 4: Testing The MAF Signal With A Multimeter
OK, your 3 previous tests have confirmed that:
- The BLK/ORG wire is delivering power (TEST 1).
- The BRN wire is delivering Ground (TEST 2).
- The RED/BLK wire is delivering Ground (TEST 3).
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 red (RED) wire, labeled as wire number 2 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 MAF sensor is defective.
NOTE: To perform this test, the MAF 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 5-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 2 (see photo above)
This wire should be the the RED wire of the connector. - 5
Start the engine and let it idle for about 5 minutes till it reaches its normal operating temperature.
- 6
At idle RPM, the base MAF signal voltage output should be 1.1 to 1.5 Volts DC.
- 7
Accelerate and decelerate the engine as you watch the multimeter's Volts DC readings.
- 8
The voltage reading should increase when you accelerate the engine and decrease when you decelerate the engine.
Let's interpret your test result:
CASE 1: The voltage readings increased and decreased as indicated. This is the correct and expected test result and tells you that the MAF sensor (on your Toyota Camry) is working correctly.
CASE 1: The voltage readings DID NOT increase or decrease as indicated. This test result tells you that the MAF sensor on your Toyota Camry is defective and needs to be replaced if you have confirmed:
- The BLK/ORG wire is delivering power (TEST 1).
- The BRN wire is delivering Ground (TEST 2).
- The RED/BLK wire is delivering Ground (TEST 3).
- The MAF signal voltage output increases/decreases as you rev up/rev down the engine (this test section).
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 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).
- How To Test The Alternator (1997-2001 3.0L V6 Toyota Camry).
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