How To Test The Camshaft Position Sensor (1996-1997 3.9L Dodge Ram Pickup)

TEST 2: Making Sure The CMP Sensor Has 5 Volts

As I mentioned before, the camshaft position sensor needs 5 Volts and Ground to create its ON/OFF voltage signal.

So in this test section, we're gonna' make sure that the violet with white stripe (VIO/WHT) wire is providing 5 Volts with the key on and engine off (KOEO).

If the CMP sensor is getting power from the VIO/WHT, then the next test is to make sure that it's getting Ground.

These are the test steps:

1. 1

   Disconnect the CMP sensor from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Turn the key on but don't crank or start the engine.

4. 4

   Connect the red multimeter test lead (using the appropriate tool) to the VIO/WHT wire identified with the number 1 in the photo above.
   
   NOTE: This test is done on the connector that has female terminals.

5. 5

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

6. 6

   Your multimeter should read 4.5 to 5 Volts

Let's analyze your test result:

CASE 1: The VIO/WHT wire is providing 5 Volts to the CMP sensor. This is the correct and expected test result.

The next test is to test for the presence of Ground in the black light blue stripe wire: TEST 3: Making Sure The CMP Sensor Has Ground.

CASE 2: The VIO/WHT wire IS NOT providing 5 Volts to the CMP sensor. Without 5 Volts the camshaft position sensor will not produce a CMP voltage signal.

The most common cause of this problem is an open-circuit problem in the VIO/WHT wire between the CMP sensor's connector and the fuel injection computer's connector.

Although it's beyond the scope of this tutorial to diagnose these missing 5 Volts, your next step is to find out why it's missing and restore it.

TEST 3: Making Sure The CMP Sensor Has Ground

Up to this point, the previous two tests have confirmed that:

• The CMP sensor's voltage signal is not switching between 5 Volts and 0 Volts.
• The CMP sensor is receiving 5 Volts from the VIO/WHT wire.

Now we're gonna verify that Ground is present in the black with light blue stripe (BLK/LT BLU) wire.

I've labeled the BLK/LT BLU wire with the number 2 in the photo above.

IMPORTANT: The fuel injection computer provides Ground to the CMP sensor. Be careful and don't short the BLK/LT BLU wire to battery power (12 Volts) or you'll fry the fuel injection computer. The multimeter voltage test I'm suggesting below (for testing the presence of Ground in this wire) is a safe and accurate test.

NOTE: Avoid probing the front of the female terminal with your multimeter test lead or you run the risk of damaging the terminal. Use a back-probe on the back of the connector or use a wire-piercing probe on the wire.

These are the test steps:

1. 1

   Disconnect the CMP sensor from its connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Turn the key on but don't crank or start the engine.

4. 4

   Connect the black multimeter test lead (using the appropriate tool) to the BLK/LT BLU wire identified with the number 2 in the photo above.
   
   NOTE: This test is done on the connector that has female terminals.

5. 5

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

6. 6

   Your multimeter should read 10 to 12 Volts DC if the BLK/LT BLU wire is providing Ground.

Let's take a look at what your test results mean:

CASE 1: Ground is present in the BLK/LT BLU wire. This is the correct test result and let's you know that the camshaft position sensor is getting Ground.

The camshaft position sensor is bad and needs to be replaced if:

• The camshaft position sensor's voltage signal is not switching ON and OFF (TEST 1).
• The VIO/WHT wire is providing the CMP sensor with 5 Volts (TEST 2).
• The BLK/LT BLU wire is providing the CMP sensor with Ground (TEST 3).

CASE 2: Ground IS NOT present in the BLK/LT BLU wire. Without Ground, the camshaft position sensor will not produce an ON/OFF voltage signal.

What's usually behind the lack of Ground is an open-circuit problem in the BLK/LT BLU wire between the CMP sensor's connector and the fuel injection computer's connector.

Although it's beyond the scope of this tutorial to check for this missing Ground, your next step is to find out why it's missing and restore it.

More 3.9L V6 Dodge Tutorials

I've written quite a few 3.9L V6 Dodge ‘how to’ tutorials that may help you troubleshoot the issues on your Dodge van, pick up or SUV. You can find all in these two indexes:

• 3.9L Dodge Index Of Articles.
• 3.9L, 5.2L, 5.9L Dodge Index Of Articles.

Here's a small sample of the articles/tutorials you'll find in the indexes:

• How To Test A No Start Condition (Dodge 3.9L, 5.2L, 5.9L).
• How To Diagnose Misfire Codes (Dodge 3.9L, 5.2L, 5.9L).
• How To Test The Fuel Injectors (Dodge 3.9L, 5.2L, 5.9L).
• How To Test The Ignition Coil -No Start Tests (Chrysler 3.9L, 5.2L, 5.9L).
• How To Test The MAP Sensor (P0107, P0108) (Dodge 3.9L, 5.2L, 5.9L).