How To Test The Camshaft Position Sensor (1998-2003 5.2L, 5.9L V8 Dodge Ram Van)

TEST 2: Making Sure The CMP Sensor Has 5 Volts

In TEST 1, you confirmed the CMP sensor's voltage isn't flipping between 5 and 0 Volts while cranking the engine.

One common reason for that —the CMP sensor isn't getting power from the PCM (the fuel injection computer).

So now we're gonna check if the violet with white stripe (VIO/WHT) wire is sending 5 Volts DC to the CMP sensor.

If that checks out, we'll move on to TEST 3 to see if the sensor's also getting a solid Ground.

Here's what to do:

1. 1

   Unplug the CMP sensor from the harness.

2. 2

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

3. 3

   Set your multimeter to DC Volts.

4. 4

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

5. 5

   Use the red multimeter lead to probe the terminal connected to the VIO/WHT wire.
   
   The VIO/WHT wire connects into the female terminal labeled number 3 in the diagram of the connector up above.
   
   NOTE: You're probing the connector with the female terminals —that's the one belonging to the engine wiring harness.

6. 6

   You should get a reading between 4.5 and 5 Volts on the multimeter.

Here's how to read the results:

CASE 1: You see 4.5 to 5 Volts on the VIO/WHT wire. Perfect. That means the CMP sensor is getting the power it needs.

Next step: Check if it's also got a solid Ground connection —go to TEST 3: Making Sure The CMP Sensor Has Ground.

CASE 2: You don't see 4.5 to 5 Volts on the VIO/WHT wire. No power means no signal —the sensor can't do its job.

This usually means there's an open or break in the VIO/WHT wire between the PCM and the sensor.

Finding and fixing that break is beyond the scope of this guide, but your next move is to trace the wire and repair the fault.

TEST 3: Making Sure The CMP Sensor Has Ground

Alright, if you've made it this far, you've already confirmed:

• TEST 1: The CMP sensor's voltage didn't flip between 0 and 5 Volts while cranking.
• TEST 2: The VIO/WHT wire is sending 5 Volts to the CMP sensor.

Now for the last check —we're gonna test the black with light blue stripe (BLK/LT BLU) wire to make sure it's giving the sensor a solid Ground.

The CMP sensor needs both power and Ground to send that ON/OFF signal (5 and 0 Volts) to the fuel injection computer (PCM).

IMPORTANT: The CMP gets its Ground directly from the PCM. Don't connect the BLK/LT BLU wire directly to 12 Volts —you'll fry the computer. The method below is totally safe for checking Ground (in the circuit) with your multimeter.

Here's how to do it:

1. 1

   Unplug the CMP sensor from its connector.

2. 2

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

3. 3

   Switch your multimeter to DC Volts.

4. 4

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

5. 5

   Touch the black multimeter lead to the female terminal for the BLK/LT BLU wire.
   
   The BLK/LT BLU wire connects into the female terminal labeled number 2 in the diagram of the connector up above.
   
   NOTE: You're probing the connector with the female terminals —that's the one belonging to the engine wiring harness.

6. 6

   You should see 10 to 12 Volts DC on the display.

Now here's how to read your result:

CASE 1: You see 10 to 12 Volts. That's what we need to see and confirms the sensor's getting Ground.

If you've confirmed all three of these:

• The signal didn't switch in TEST 1,
• The VIO/WHT wire gave you 5 Volts in TEST 2,
• And now the BLK/LT BLU wire shows proper Ground —

Then the CMP sensor is bad. Time to replace it.

CASE 2: You don't see any voltage on the meter. That means there's no Ground, and the sensor can't do its job.

That usually points to a break in the BLK/LT BLU wire between the connector and the PCM.

Finding that broken Ground wire goes beyond the scope of this tutorial —but your next step is to track it down and fix the problem.

More 5.2L, 5.9L V8 Dodge Ram Van Diagnostic Tutorials

I've written quite a few 'how to' diagnostic tutorials for the V8 Dodge Ram van and you can find them in this index:

• 5.2L, 5.9L V8 Dodge Ram Van Index Of Articles.

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

• Testing The Front Oxygen Sensors (1996-2003 5.2L, 5.9L V8 Dodge Ram Van).
• How To Test The Intake Air Temp (IAT) Sensor (1998-2003 5.2L, 5.9L V8 Dodge Ram Van).
• How To Test The TPS (1997-2003 5.2L, 5.9L V8 Dodge Ram Van).
• How To Test The MAP Sensor (1998-2003 5.2L, 5.9L V8 Dodge Ram Van).