How To Test The Crankshaft Position Sensor (1998-2001 3.9L V6 Dodge Ram Pickup)

TEST 2: Making Sure The CKP Sensor Has Power

The crankshaft position (CKP) sensor needs both power and Ground to do its job (it's a Hall-Effect type sensor). So in this part of the test, you'll use your multimeter and check if the sensor's actually getting power.

That power comes in as a 5 Volt DC signal, sent from the PCM when the key's turned to the ON position —and also while the engine's cranking or running.

It's the purple with white stripe (PPL/WHT) wire that delivers those 5 Volts to the CKP sensor.

Here's how to run this test:

1. 1

   Unplug the CKP sensor from the engine harness.

2. 2

   Connect the black lead of your multimeter to the battery's negative (-) terminal.

3. 3

   Turn the ignition key to the ON position. You don't need to start or crank the engine.

4. 4

   Set the multimeter to Volts DC.

5. 5

   Touch the red multimeter lead to terminal 1 of the harness connector.
   
   Check that the terminal actually connects to the PPL/WHT wire (PPL/WHT = VIO/WHT).
   
   NOTE: You're testing the engine wiring harness connector —the one with the female terminals.

6. 6

   Your meter should read between 4.5 and 5 Volts DC if the PCM is delivering power like it's supposed to.

Now, here's what those results tell you:

CASE 1: You're reading 4.5 to 5 Volts DC. That confirms the PCM is sending power to the CKP sensor like it should.

The next step is to check for a good Ground. Head here for that: TEST 3: Making Sure The CKP Sensor Has Ground.

CASE 2: You're not seeing 4.5 to 5 Volts DC. Go back and recheck your connections, then run the test one more time to rule out a bad contact.

If you still don't get 5 Volts, there's your issue: the CKP sensor isn't the root of the problem —it's just not being powered. Replacing the sensor won't do anything. You've got fix that power issue.

Figuring out why the power's missing is beyond this guide, but once you solve it, your V6 Dodge Ram pickup should fire right up again.

TEST 3: Making Sure The CKP Sensor Has Ground

Up to this point, your CKP sensor tests have confirmed two things:

• TEST 1: The CKP sensor isn't generating an ON/OFF voltage signal.
• TEST 2: The sensor is getting a steady 5 Volts DC.

Now it's time for the final check —you're gonna make sure the sensor has a solid Ground with a quick multimeter voltage test.

The Ground for the CKP sensor comes through the black with light blue stripe (BLK/LT BLU) wire, which runs straight from the PCM (the engine's fuel injection computer).

IMPORTANT: That BLK/LT BLU wire is connected directly to the PCM —if you connect it to battery voltage, you'll fry the computer. So take care. The test method below is a safe way to check for Ground in this circuit.

Here's what you need to do next:

1. 1

   Unplug the CKP sensor from the engine harness.

2. 2

   Connect the red lead of your multimeter to the battery's positive (+) terminal.

3. 3

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

4. 4

   Set your multimeter to Volts DC mode.

5. 5

   Touch the black multimeter lead to terminal number 2 on the CKP connector.
   
   Make sure you're probing the terminal linked to the BLK/LT BLU wire.

6. 6

   If Ground is present, your multimeter should read somewhere between 10 and 12 Volts DC.

Let's interpret the results:

CASE 1: You're reading between 10 and 12 Volts DC. That tells you the BLK/LT BLU wire is delivering a good Ground to the CKP sensor.

If you've confirmed all three test steps:

• TEST 1: The CKP sensor isn't sending out its ON/OFF 5V signal.
• TEST 2: It's getting 4.5 to 5 Volts.
• This test: It's also receiving proper Ground.

Then it's clear that the CKP sensor has failed and needs to be replaced.

CASE 2: You didn't get a voltage reading between 10 and 12 Volts DC. Double-check your test connections and give it another go.

If the reading still doesn't show up, then the BLK/LT BLU wire isn't Grounding the sensor. So the sensor itself isn't the problem —the real issue is that missing Ground. Fixing that is your next step toward getting the engine to start again.

More 3.9L V6 Dodge Ram Pickup Tutorials

You can find a complete list of wiring diagrams and diagnostic tutorials for the V6 Dodge Ram pickup here:

• 3.9L V6 Dodge Ram Index Of Articles.

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

• How To Test The TPS (1997-2001 3.9L V6 Dodge Ram Pickup).
• Testing The Front Oxygen Sensor's Performance (1996-2001 3.9L V6 Dodge Ram Pickup).
• How To Test The Fuel Pump (1992-2001 3.9L V6 Dodge Ram Pickup).
• How To Test The Intake Air Temp (IAT) Sensor (1998-2001 3.9L V6 Dodge Ram Pickup).