This step-by-step guide will show you how to test the CMP sensor's performance —no scan tool needed.
All you need is a multimeter to confirm the CMP sensor is generating an ON/OFF signal pulse and find out if it's the source of your engine trouble.
I'll guide you through the diagnostic process in plain language with clear steps. It's 100% DIYer-friendly and designed to save you time and headaches.
Contents of this tutorial:
- Symptoms Of A Bad CMP Sensor.
- 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: Testing The CMP Signal With A Multimeter.
- TEST 2: Making Sure The CMP Sensor Is Getting 8 Volts.
- TEST 3: Making Sure The CMP Sensor Is Getting Ground.
- Installing The CMP Sensor: Air Gap Clearance.
- More 3.3L V6 Chrysler, Dodge, And Plymouth Minivan Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 3.3L V6 Chrysler Town & Country: 1998, 1999, 2000.
- 3.3L V6 Chrysler Voyager: 2000.
- 3.3L V6 Dodge Caravan: 1998, 1999, 2000.
- 3.3L V6 Dodge Grand Caravan: 1998, 1999, 2000.
- 3.3L V6 Plymouth Voyager: 1998, 1999, 2000.
- 3.3L V6 Plymouth Grand Voyager: 1998, 1999, 2000.
OTHER CMP SENSOR TESTS:
- How To Test The CMP Sensor (1990-1993 3.3L V6 Chrysler, Dodge, And Plymouth Minivan).
- How To Test The CMP Sensor (1994-1997 3.3L V6 Chrysler, Dodge, And Plymouth Minivan).
Symptoms Of A Bad CMP Sensor
The camshaft position sensor plays a key role in engine timing and injector firing. When it fails in your 3.3L V6 equipped minivan, here's what you'll likely experience:
- Crank but no-start: Without a valid cam signal, the PCM can't command ignition or fuel injection properly.
- Hard starts: It may take a few extra seconds of cranking before the engine starts running.
- Sudden stalls: A faulty sensor can interrupt the engine mid-drive or while idling at a stoplight.
- Misfires and rough idle: The engine can feel shaky, with RPM fluctuations or erratic firing (happens when CMP sensor is failing but not completely dead yet).
- Lack of power: Acceleration becomes weak, and engine response feels bogged down.
- Check engine light with P0340: This code points directly to the cam sensor circuit.
How The CMP Sensor Works
The cam sensor on these late-'90s 3.3L engines is a Hall-Effect device that works by switching voltage on and off as a trigger rotates past its magnetic element. It receives both power and Ground from the PCM, and in return, it sends a digital signal back.
This signal comes in the form of a square wave —a rapid alternating pattern of high and low voltage levels. When "ON", it delivers 5 Volts. When "OFF", it drops to a lower voltage, typically between 0.3 and 0.5 Volts.
This repeating signal helps the PCM identify where the camshaft is in its rotation, ensuring the engine stays in sync during startup and normal operation.
Should I Just Replace The CMP Sensor Without Testing It?
Most folks, even repair shops, will simply replace the CMP sensor when a code like P0340 shows up —and in most cases, that's exactly what solves the issue.
The part's not expensive, and if you're in a hurry, replacing it right away is a perfectly reasonable move.
Just make sure to check the links below before buying —they might save you a few bucks.
Of course, if you're the kind of person who likes to be sure before replacing anything, this tutorial covers how to test it step-by-step.
NOTE: If you're installing a new sensor or removing and reinstalling the same one, see: Installing The CMP Sensor: Air Gap Clearance.
Where To Buy The CMP Sensor And Save
The following links will help you comparison shop for the camshaft position sensor:
CMP Spacer: Air Gap Spacer
NOTE: If you're installing a new sensor or removing and reinstalling the same one, see: Installing The CMP Sensor: Air Gap Clearance.
Camshaft Position Sensor Connector Pinout
| CMP Sensor Circuits | ||
|---|---|---|
| Terminal | Wire | Description |
| 1 | Orange (ORG) | 8 Volts DC |
| 2 | Black with light blue stripe (BLK/LT BLU) | Ground |
| 3 | Tan with yellow stripe (TAN/YEL) | CMP Sensor Signal |
TEST 1: Testing The CMP Signal With A Multimeter
In this first test, we'll check if the CMP sensor is creating an ON/OFF 5 Volt signal as the engine turns.
Specifically, we're looking for a voltage that toggles between ON and OFF —the key indicator that the sensor is functioning correctly:
- ON: Signal voltage at 5 Volts.
- OFF: Signal voltage at 0 Volts.
If you don't have a multimeter or need to upgrade yours? This is the one I use and recommend: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (at: amazon.com).
NOTE: You won't be using the starter motor for this test. Instead, you'll rotate the engine manually by hand at the crankshaft pulley (using a ratchet and socket).
CAUTION: If you need to lift the front of the minivan to access the crankshaft pulley bolt, make sure to securely place the vehicle on jack stands. Never trust the jack alone to support the vehicle.
SIGNAL ACCESS: To access the CMP signal, the sensor must stay connected during the test. So, you'll use a back probe (on the connector) or a wire piercing probe (on the wire) to read the signal. You can see an example of this tool here (and where to buy it): Wire Piercing Probe.
OK, let's begin:
- 1
Start by disconnecting the coil pack.
This prevents the engine from accidentally starting while testing the CMP signal. - 2
Set the multimeter to DC voltage.
- 3
Ground your black multimeter lead on the negative (-) battery terminal.
- 4
Connect the red multimeter test lead to the CMP signal wire.
Back probe the connector or pierce the signal wire, then hook up your red lead to that point. - 5
Turn the ignition key to ON, but don't crank the engine.
- 6
Manually rotate the crankshaft pulley slowly.
Use a ½-inch ratchet and socket to turn the pulley clockwise —take your time. - 7
You should see the signal voltage switch between 5V (ON) and 0.3–0.5V (OFF) on your multimeter's display.
Let's see what your test result is telling us:
CASE 1: You saw an ON/OFF signal. That's a pass.
If the multimeter clearly switched between 5V and around 0.3V as you turned the crankshaft, it means the CMP sensor is working. You've just confirmed it's getting both voltage and Ground, and producing the correct signal output.
CASE 2: Flat reading, no voltage change. Time to dig a bit deeper.
Double-check your multimeter setup —a loose connection or testing the wrong wire can throw things off.
If it's still not generating the ON/OFF voltage pulse after confirming your test connections, we need to check that the sensor is getting 8 Volts. Go to: TEST 2: Making Sure The CMP Sensor Is Getting 8 Volts.