In this tutorial, I'll show you step-by-step how to test the camshaft position (CMP) sensor on your 2002-2007 4.7L V8 Dodge Ram pickup —using nothing more than a multimeter.
A faulty CMP sensor can cause no-start problems, stalling, rough idle, or loss of power —and will usually trigger a P0340 trouble code (camshaft signal missing).
In some cases, you may also see an intermittent P0344 code if the sensor signal is weak or cutting out.
I'll explain how the sensor works, what symptoms to watch for, and how to test the CMP sensor —so you can confirm whether it really needs replacing.
And hey, if you'd rather just replace the sensor without testing it, that's totally fine too —I've included links below to help you find a quality replacement at a good price.
Contents of this tutorial:
- Common Symptoms Of A Bad CMP Sensor (P0340).
- How The CMP Sensor Works.
- Should I Just Replace The CMP Sensor Without Testing It?
- Where To Buy The CMP Sensor And Save.
- Camshaft Position Sensor Connector Pinout.
- TEST 1: Checking The CMP Signal With A Multimeter.
- TEST 2: Making Sure The CMP Sensor Is Getting 5 Volts.
- TEST 3: Making Sure The CMP 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 Pickup: 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009.
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 CKP Sensor -P0320, P0335, P0339 (2002-2010 4.7L V8 Dodge Ram Pickup).
Common Symptoms Of A Bad CMP Sensor (P0340, P0344)
A failed or faulty camshaft position (CMP) sensor on your 2002-2007 4.7L V8 Dodge Ram pickup can cause anything from a simple rough idle to a no-start condition.
Since the PCM needs a clean cam signal to properly time fuel injection and ignition, when the CMP sensor fails, here's what typically happens:
- Engine cranks but won't start: No spark or fuel because the PCM can't sync the camshaft signal.
- Code P0340: The PCM flags a missing cam signal and shuts down fuel and spark output.
When the sensor is starting to go out (intermittent failure), symptoms can be more random. Keep an eye out for these:
- Starts, then stalls: Engine may fire up briefly but die as soon as the signal cuts out.
- Check Engine Light ON: You'll usually see one of these:
- P0340: Camshaft Position Sensor Circuit.
- P0344: Camshaft Position Sensor Intermittent.
- Poor running: Surging, hesitation, rough idle, or misfires —all signs the PCM is struggling to keep timing in sync.
How The CMP Sensor Works
The camshaft position (CMP) sensor on your 2002-2007 4.7L V8 Dodge Ram pickup is a 3-wire Hall-effect sensor. It receives 5 Volt power and Ground straight from the PCM —no external relays or fuses involved.
In a nutshell, here's what happens as the engine turns:
- The camshaft spins —during cranking or normal engine operation.
- The CMP sensor detects camshaft position and sends a pulsed ON/OFF voltage signal back to the PCM.
- ON pulse: About 5 Volts.
- OFF pulse: Drops to roughly 0.3 to 0.5 Volts.
The PCM uses this pulsing ON/OFF signal (along with the CKP sensor signal) to initiate and keep fuel injection and spark timing perfectly synced to the correct firing order.
If the CMP signal is missing or drops out —whether while cranking or running— the PCM loses timing sync. The result? A P0340 code (no cam signal), a possible P0344 (intermittent signal), and in many cases, the engine won't start at all.
Should I Just Replace The CMP Sensor Without Testing It?
When a P0340 code shows up in the PCM, most folks —and plenty of shops— skip straight to replacing the camshaft position (CMP) sensor without running any tests.
And honestly? That quick-swap approach works more often than not. If the CMP sensor was faulty, a new one clears the P0340 DTC, restores engine sync, and gets the truck running again.
If that's your plan —no worries. I'll include links below to quality brand-name sensors (not cheap knockoffs) so you can avoid problems down the road.
But if you'd rather test the CMP sensor first— especially if you're chasing an intermittent P0344 or don't want to waste money— this tutorial will show you exactly how to do it step-by-step with just a multimeter.
Where To Buy The CMP Sensor And Save
Camshaft Position Sensor Connector Pinout
| 2002-2003 CMP Sensor Circuits | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Tan with yellow stripe (TAN/YEL) | CMP Sensor Signal |
| 2 | Black with light blue stripe (BLK/LT BLU) | Ground |
| 3 | Orange (ORG) -2002 | 5 Volts DC |
| Violet with white stripe (VIO/WHT) -2003 | ||
| 2004-2007 CMP Sensor Circuits | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Dark blue with gray stripe (DK BLU/GRY) | CMP Sensor Signal |
| 2 | Dark blue with dark green stripe (DK BLU/DK GRN) | Ground |
| 3 | Yellow with pink stripe (YEL/PNK) | 5 Volts DC |
TEST 1: Checking The CMP Signal With A Multimeter
First up, we're going to test whether your camshaft position (CMP) sensor is producing a proper ON/OFF voltage signal —and we'll do this by manually turning the engine with a ratchet on the crankshaft pulley bolt.
Why by hand? Because using the starter motor spins the crankshaft too fast —your multimeter won't catch the CMP sensor's signal changes at that speed. But by rotating the crank slowly, you'll see the voltage toggle clearly between ON (5V) and OFF (~0V) right on your multimeter.
If you 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).
NOTE: The sensor must stay plugged in for this test. You'll either back-probe the connector or use a wire-piercing probe on the wire. If you need one, you can see an example of one and where to buy it: Wire Piercing Probe.
CAUTION: If you need to raise the front of the truck for crankshaft pulley bolt access, always use jack stands —never rely on a floor jack alone.
Here's how to test the CMP sensor step-by-step:
- 1
Disconnect all 8 ignition coils.
NOTE: This is a safety precaution to prevent accidental engine start-up during the test. - 2
Set your multimeter to DC Volts mode.
- 3
Connect your black multimeter lead to battery negative (-) post.
- 4
Probe the CMP signal wire of the CMP sensor connector with your red multimeter lead.
NOTE: The signal wire is either a TAN/YEL wire (2002-2003) or a DK BLU/GRY wire (2004-2007).
You'll need to back-probe the connector or pierce the wire to access the signal. - 5
Rotate the crankshaft pulley clockwise by hand using a 1/2-inch ratchet and socket.
NOTE: Don't use the starter motor to crank the engine. - 6
Watch the multimeter —the voltage should toggle between 5V and about 0V.
ON = about 5 Volts. OFF = around 0.3–0.5 Volts (which counts as 0V for this test).
IMPORTANT: Rotate the crankshaft through at least 2 full turns —this ensures you see a full CMP signal cycle.
Let's interpret that multimeter reading:
CASE 1: Clean ON/OFF voltage pattern. That's what you want —the CMP sensor is generating a valid signal to the PCM.
If you're seeing a P0340 or P0344, this test results suggests the sensor itself is working— you may need to look at wiring or intermittent faults.
CASE 2: No ON/OFF signal. First double-check your connections and settings and redo the test.
If you still get no signal, next step is to verify the CMP sensor's power supply, go to: TEST 2: Making Sure The CMP Sensor Is Getting 5 Volts.