How To Test The Cam Sensor (P0341) (GM 3.1L, 3.4L)

TEST 2: Making Sure The CMP Sensor Is Getting 12 Volts

The wire that supplies 12 Volts to the camshaft position sensor is the wire labeled the letter A in the photo above.

We can easily check for the presence of these 12 Volts in the wire by doing a simple multimeter voltage test.

NOTE: Avoid probing the front of the female terminal with your multimeter test lead. Use a back probe or a wire piercing probe instead.

Let's get testing:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the CMP sensor from its electrical connector.

3. 3

   With the red multimeter test lead and an appropriate tool probe the wire labeled with the letter A in the photo above.
   
   NOTE: This test is done on the engine wiring harness connector.

4. 4

   Connect the black multimeter test lead to the negative (-) battery terminal.

5. 5

   Turn the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 10 to 12 Volts.

Let's analyze your test result:

CASE 1: 10 to 12 Volts are present. This is the correct test result and confirms that the camshaft position sensor is getting the power it needs to function.

The next step is to verify that the CMP sensor is getting Ground. For this last test go to: TEST 3: Making Sure The CMP Is Getting Ground.

CASE 2: 10 to 12 Volts ARE NOT present. This test result confirms that the CMP sensor is not getting power.

The most likely reasons for this are:

• The wire has open-circuit problem.
• The fuel injection computer may be fried (although a very rare thing to happen).

Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the camshaft position (CMP) sensor itself as bad.

TEST 3: Making Sure The CMP Sensor Is Getting Ground

You camshaft position sensor test results have, up to this point, confirmed that:

• The CMP signal voltage did not pulse ON/OFF in TEST 1.
• The camshaft position sensor is getting 10 to 12 Volts DC in TEST 2.

The last test we'll do is confirm that Ground is being supplied to the CMP sensor.

The wire that we're gonna' test, for the presence of Ground, is the wire labeled with the letter C in the photo above.

IMPORTANT: The fuel injection computer is the one that provides this Ground internally, so be careful and don't accidentally or intentionally apply power (12 Volts) to this wire or you'll fry the fuel injection computer.

OK, here are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the CMP sensor from its electrical connector.

3. 3

   With the black multimeter test lead and an appropriate tool probe the wire labeled with the letter C in the photo above.
   
   NOTE: This test is done on the engine wiring harness connector.

4. 4

   Connect the red multimeter test lead to the positive (+) battery terminal.

5. 5

   Turn the key to its ON position but don't start the engine.

6. 6

   The multimeter should display 10 to 12 Volts.

Let's take a look at your test results:

CASE 1: The multimeter showed 10 to 12 Volts. This is the correct test result and tells you that the CMP sensor is getting Ground.

The CMP sensor is bad and needs to be replaced only if you have:

1. Confirmed that CMP signal voltage does not pulse ON/OFF in TEST 1.
2. Confirmed that the camshaft position sensor is getting 10 to 12 Volts DC in TEST 2.
3. In this test section, you have confirmed that the camshaft position sensor is receiving Ground.

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CASE 2: The multimeter DID NOT show 10 to 12 Volts. This test result confirms that the CMP sensor is not receiving Ground. Without Ground the camshaft position sensor will not create its CMP signal.

The most likely reasons for this missing Ground are:

• The wire has open-circuit problem.
• The fuel injection computer may be fried (although a very rare thing to happen).

Altho' it's beyond the scope of this tutorial to test these conditions, you have now eliminated the camshaft position (CMP) sensor itself as bad.

More GM 3.1L, 3.4L Test Articles

I've written several 3.1L and 3.4L troubleshooting articles that may be of interest to you. You can access all of them in this index: GM 3.1L, 3.4L Index Of Articles.

Here's a sample of the diagnostic test tutorials you'll find in the index:

1. How To Test The 24X Crank Sensor (GM 3.1L, 3.4L).
2. How To Test The Blower Motor (GM 3.1L, 3.4L).
3. How To Test The MAP sensor with a multimeter (GM 2.8L 3.1L, 3.4L).
4. How To Troubleshoot A No Start (GM 3.1L, 3.4L).
5. Testing The Ignition Module And Crank Sensor (7X Crank Sensor) (GM 3.1L, 3.4L) (at: easyautodiagnostics.com).