In this tutorial, I'm going to show you how to test the crankshaft position sensor (CKP) on your 2002-2010 4.7L V8 Dodge Ram Pickup —step-by-step, using nothing more than a multimeter.
A failing CKP sensor can cause all kinds of problems, from a no-start condition to a loss of power, or even sudden engine stalling.
If your pickup is showing codes P0320, P0335, or P0339, this is one of the first things you should check.
I'll show you how the sensor works, how to test it, and how to tell if it's really the cause of your engine troubles —before you spend money on parts.
And if you're already planning on replacing the sensor without testing it, no worries —I'll show you where to get a good deal on one.
Let's get started!
Contents of this tutorial:
- Symptoms Of A Bad CKP Sensor.
- How The CKP Sensor Works.
- Should I Just Replace The CKP Sensor Without Testing It?
- Where To Buy The CKP Sensor And Save.
- Crankshaft Position Sensor Connector Pinout.
- TEST 1: Checking The CKP Signal With A Multimeter.
- TEST 2: Making Sure The CKP Sensor Is Getting 5 Volts.
- TEST 3: Making Sure The CKP Sensor Is Getting Ground.
- More 4.7L V8 Dodge Ram Pickup Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 4.7L V8 Dodge Ram 1500: 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010.
WIRING DIAGRAMS:
- Ignition System Wiring Diagram (2002 4.7L V8 Dodge Ram Pickup).
- Ignition System Wiring Diagram (2003 4.7L V8 Dodge Ram Pickup).
- Ignition System Wiring Diagram (2004-2006 4.7L V8 Dodge Ram Pickup).
- Ignition System Wiring Diagram (2007-2008 4.7L V8 Dodge Ram Pickup).
- Ignition System Wiring Diagram (2009-2010 4.7L V8 Dodge Ram Pickup).
IGNITION SYSTEM TESTS:
- How To Test The COP Ignition Coils (Chrysler, Dodge, Jeep 4.7L).
- How To Test The CMP Sensor -P0340 (2002-2007 4.7L V8 Dodge Ram Pickup).
Symptoms Of A Bad CKP Sensor
The PCM (Powertrain Control Module) on your 2002-2010 4.7L V8 Dodge Ram pickup relies on information from both the crankshaft position (CKP) sensor and the camshaft position (CMP) sensor to start ignition spark, control fuel injection, and manage ignition spark timing.
If either of these two sensors fail —or start sending erratic signals— the PCM won't know the exact position of the crankshaft, and this can cause one or more of the following problems:
- Engine cranks but won't start: The starter motor engages the engine, but no matter how long you crank it, it won't start.
- Hard starting: You have to crank the engine a long time before it finally starts.
- Sudden engine stall: Engine dies without warning while running.
- Rough idle: Especially if the CKP sensor is starting to fail but hasn't completely died yet.
- Lack of power: Common issue when the sensor is starting to fail but hasn't completely died yet.
- Check Engine Light ON: One of the following diagnostic trouble codes (DTCs) stored in memory:
- P0320: No Crank Reference Signal At PCM.
- P0335: Crankshaft Position Sensor Circuit.
- P0339: Crankshaft Position Sensor Intermittent.
How The CKP Sensor Works
The crankshaft position sensor (CKP) on your 2002-2010 4.7L V8 Dodge Ram is a 3-wire Hall-effect sensor. It gets its 5 Volt power supply and Ground directly from the PCM —no external fuses or relays involved.
Its job is simple but critical: to track crankshaft position and rotation speed in real time, so the PCM can manage ignition timing and fuel injection.
Here's how it does that:
- As the engine cranks or is running, it monitors notches cut into a tonewheel on the crankshaft.
- As the crankshaft rotates, the tonewheel passes by the sensor's tip, triggering a series of ON (5 Volt) and OFF (0 Volt) voltage pulses.
- The PCM uses these ON/OFF pulses to calculate crankshaft position and RPM —constantly adjusting spark and fuel delivery as needed.
- The CKP sensor also works hand-in-hand with the camshaft position sensor (CMP) to keep everything in sync.
If the PCM loses this signal —or if the signal becomes erratic— it can't manage engine operation properly. When this happens, you'll usually see one or more of these trouble codes show up: P0320, P0335, or P0339.
Sensor location: On the 4.7L V8, the CKP sensor is mounted on the right rear side of the engine block, in a machined hole on the side of the cylinder block.
Should I Just Replace The CKP Sensor Without Testing It?
When a CKP sensor code like P0320, P0335, or P0339 shows up, most folks skip testing it entirely and just replace it and move on.
And to be fair, that approach often works. A new sensor gets installed, codes are cleared, and the pickup fires right up again.
There's a good reason for this "replace first" strategy:
- Replacement sensors aren't that expensive —and they're a known failure point on these engines.
- Getting a multimeter or scope on the sensor while it's still installed is a process (not difficult, but still time consuming) —it's tucked down on the engine block, so it's not the most accessible sensor on your pickup.
So if you'd rather just swap it, that's a valid option —and I'll link to a quality sensor down below.
But if you prefer to confirm the sensor is really bad before spending the money, no problem —this guide will show you exactly how to test it, step-by-step, so you can know for sure.
Where To Buy The CKP Sensor And Save
The following links will help you comparison shop for the crankshaft position sensor:
Crankshaft Position Sensor Connector Pinout
| 2002-2003 CKP Sensor Circuits | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Orange (ORG) | 5 Volts DC |
| 2 | Black with light blue stripe (BLK/LT BLU) | Ground |
| 3 | Grey with black stripe (GRY/BLK) | CKP Sensor Signal |
| 2004-2010 CKP Sensor Circuits | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Pink with yellow stripe (PNK/YEL) | 5 Volts DC |
| 2 | Dark blue with dark green stripe (DK BLU/DK GRN) | Ground |
| 3 | Brown with light blue stripe (BRN/LT BLU) | CKP Sensor Signal |
TEST 1: Checking The CKP Signal With A Multimeter
The first thing we're going to do is verify if the crankshaft position sensor (CKP) is producing its ON/OFF signal. You'll do this test by manually turning the engine by hand —not with the starter motor.
With this test we'll know right away if the sensor signal is missing, and if it is, it confirms that the CKP sensor DTC (P0320, P0335, or P0339) is telling the truth and that the CKP sensor is the cause of your pickup's no-start or other drivability issues.
Here's what you'll need:
- Socket + 1/2" ratchet (to turn the crankshaft pulley).
- Digital multimeter (set to DC Volts).
- Wire piercing probe or back-probe tool.
And here's what you'll see during the CKP sensor signal output test:
- ON: Voltage jumps to 5 Volts.
- OFF: Drops back near 0 Volts.
The signal wire you'll be testing, and the one that delivers the CKP sensor signal to the PCM, is the:
- 2002-2003: grey with black stripe (GRY/BLK) wire.
- 2004-2010: brown with light blue stripe (BRN/LT BLU) wire.
Don't have a multimeter, or thinking about upgrading? Here's the one I personally use and recommend: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (via Amazon).
IMPORTANT: You must leave the sensor plugged in —and you'll be back-probing or piercing the signal wire. If you disconnect the sensor, it won't produce a signal. If you need a good wire piercing probe, check out this one: Wire Piercing Probe.
NOTE: Don't use the starter motor to crank the engine during this test —it'll spin the engine too fast for the multimeter to catch the voltage change. You'll need to rotate the crankshaft slowly by hand.
Let's get this show on the road:
- 1
Disconnect all 8 ignition coils —this will prevent the engine from accidentally starting during the test.
- 2
Set your multimeter to DC Volts mode.
- 3
Connect the black lead to the battery negative (-) terminal.
- 4
Back-probe or pierce the BRN/LT BLU (or GRY/BLK) signal wire with your red lead.
NOTE: If you had to disconnect the connector to attach the probe, be sure to reconnect it to the sensor before moving on to the next step. - 5
Turn the ignition key ON (engine OFF).
- 6
Use a ratchet to slowly rotate the crankshaft pulley by hand.
NOTE: Rotate at least one full revolution —this ensures all tonewheel slots pass by the sensor. - 7
Watch your multimeter for voltage changes:
Voltage should toggle between 5V and 0V as you turn the crankshaft pulley.
On early 2002 pickups (with a 3-connector PCM), you'll see 16 ON/OFF pulses per full crankshaft revolution.
On late 2002 through 2010 pickups (with a 4-connector PCM), you'll see 32 ON/OFF pulses per full crankshaft revolution.
How to interpret the results:
CASE 1: You see a clean ON/OFF pattern. The sensor is working and sending proper data to the PCM.
If you were chasing a P0320, P0335, or P0339, this confirms the CKP sensor itself is not the issue.
CASE 2: No signal (flat voltage). Double-check your test connections and repeat the test.
If you still get no reading, your next step is to check that the CKP sensor is getting power. Go to: TEST 2: Making Sure The CKP Sensor Is Getting 5 Volts.