How To Test The Camshaft Position Sensor (1992-1995 3.9L V6 Dodge Ram Van)

TEST 2: Making Sure The CMP Sensor Has 8 Volts

So far, TEST 1 shows that the CMP sensor isn't putting out an ON/OFF voltage signal.

One common reason for that? It's not getting power from the fuel injection computer.

This power comes in the form of 8 Volts DC, delivered through the orange (ORG) wire of the CMP sensor's engine harness connector.

If you look at the connector illustration above, I've marked the terminal that supplies this 8 Volt feed with the number 1.

Alright, here's how to check it:

1. 1

   Disconnect the CMP sensor from its connector.

2. 2

   Connect the black lead from your multimeter to the battery's negative (-) post.

3. 3

   Switch your multimeter to Volts DC mode.

4. 4

   Turn the key to the ON position —but don't crank the engine.

5. 5

   Touch the red meter lead to the terminal that connects to the ORG wire.
   
   NOTE: You're testing the engine wiring harness connector here —the one with the female terminals.

6. 6

   Your multimeter should read somewhere between 7.5 and 8 Volts.

Here's what your results tell you:

CASE 1: The ORG wire is showing 7.5 to 8 Volts. That's exactly what you wanna see —it confirms the sensor's getting the power it needs.

Next up, we've gotta make sure the BLK/LT BLU wire has a good Ground connection. Head over here to do that: TEST 3: Making Sure The CMP Sensor Has Ground.

CASE 2: The ORG wire IS NOT showing 7.5 to 8 Volts. Without that power, the camshaft position sensor won't be able to send out its signal.

This usually means there's a break or open-circuit in the ORG wire between the CMP sensor's connector and the computer's connector.

This guide doesn't cover tracking down that kind of wiring issue —but that's your next step: figure out what's blocking the power and get it fixed.

TEST 3: Making Sure The CMP Sensor Has Ground

Your last two tests confirmed the following:

• The CMP sensor isn't switching between 5 and 0 Volts while the engine's cranking (TEST 1).
• The ORG wire is sending 7.5 to 8 Volts to the sensor like it should (TEST 2).

Now it's time for the final test —we need to make sure the CMP sensor is getting a solid Ground connection through the black with light blue stripe (BLK/LT BLU) wire.

To check that Ground, we're gonna use the multimeter to do a quick voltage test right on the BLK/LT BLU wire.

IMPORTANT: Whatever you do, don't let the BLK/LT BLU wire touch 12 Volts from the battery —that'll damage the fuel injection computer. The method I show below is safe and gets the job done without any risk of damage to the computer.

Let's dive in:

1. 1

   Disconnect the CMP sensor from its connector.

2. 2

   Hook up the red lead from your multimeter to the battery's positive (+) post.

3. 3

   Switch the multimeter over to DC Volts mode.

4. 4

   Turn the key to the ON position —but don't crank or start the engine.

5. 5

   Touch the black meter lead to the terminal that connects to the BLK/LT BLU wire.
   
   NOTE: You're testing the engine wiring harness connector here —the one with the female terminals.

6. 6

   If the wire's Grounded properly, your meter should read between 10 and 12 Volts.

Let's break down what those results tell us:

CASE 1: The BLK/LT BLU wire is providing Ground. That's the result you're looking for —it means the CMP sensor is getting the Ground it needs.

You can now be sure the CMP sensor is bad and needs replacing only if you've confirmed all three of the following:

• It's not producing an ON/OFF signal (TEST 1),
• It's receiving 7.5 to 8 Volts (TEST 2), and
• It's got a solid Ground connection (this test).

CASE 2: The BLK/LT BLU wire IS NOT providing Ground. If there's no Ground, the CMP sensor can't send out its ON/OFF voltage signal —simple as that.

This usually means there's a break or open spot in the BLK/LT BLU wire somewhere between the sensor's connector and the computer's connector.

This guide doesn't go into tracking that down, but your next move is clear: find where the Ground connection is lost —and fix it.

More 3.9L V6 Dodge Ram Vans Diagnostic Tutorials

I've written quite a few 'how to' diagnostic tutorials for the V6 Dodge Ram van and you can find them in this index:

• 3.9L V6 Dodge Ram Van Index Of Articles.

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

• How To Test The Intake Air Temp (IAT) Sensor (1992-1997 3.9L V6 Dodge Ram Van).
• How To Test The MAP Sensor (1992-1997 3.9L V6 Dodge Ram Van).
• How To Test The Fuel Pump (1992-2003 3.9L V6 Dodge Ram Van).
• How To Test For A Blown Head Gasket (1989-2003 3.9L V6 Dodge Ram Van).