How To Test The CMP Sensor -P0340 (2001-2002 2.4L Chrysler And Dodge Minivan)

TEST 2: Confirming The CMP Sensor Is Getting 8 Volts

In this step, we're going to check if the orange (ORG) wire is supplying the CMP sensor with 8 Volts —just like it should.

This wire connects to pin 1 of the CMP sensor's 3-wire connector. You'll find it labeled in the connector pinout diagram above.

This 8 Volt power supply comes straight from your minivan's PCM (Powertrain Control Module) and to test for it —we'll do a simple multimeter voltage test with the key in the ON (RUN) position (but engine OFF).

Let's walk through the test:

1. 1

   Disconnect the CMP sensor from its connector so you can access the terminals.

2. 2

   Set your multimeter to measure DC Voltage.

3. 3

   Connect the black meter lead to the battery's negative (-) terminal.

4. 4

   Use the red lead to gently probe terminal 1 at the sensor connector.
   
   NOTE: Make sure you're that terminal 1 connects to the ORG wire.

5. 5

   Have your assistant turn the ignition key to RUN, without cranking the engine.

6. 6

   Your multimeter should display somewhere between 7 and 8 Volts DC.

Let's see what your test result means:

CASE 1: You're seeing 7 to 8 Volts on the multimeter. That's exactly what we want. It means the CMP sensor is getting the power supply it needs to create its ON/OFF signal.

With power confirmed, the next step is checking the Ground wire. Continue to: TEST 3: Making Sure The CMP Sensor Is Getting Ground.

CASE 2: No voltage. Recheck your test connections and repeat the test.

If you still don't see 8 Volts, that means the CMP sensor isn't getting the power it needs —and that's a big clue if you're chasing code P0340.

The most common cause here is a break or open in the ORG wire between the sensor and the PCM —and not a bad sensor itself.

Your next step is to troubleshoot and solve the issue causing these missing 8 Volts to get the CMP sensor back to work and resolve code P0340.

TEST 3: Making Sure The CMP Sensor Is Getting Ground

So far, your CMP sensor diagnostic tests have confirmed:

• The sensor isn't generating an ON/OFF voltage signal (see TEST 1).
• It's receiving the correct 8 Volt power supply (see TEST 2).

Now it's time to check that the CMP sensor is getting a reliable Ground through the black with light blue stripe (BLK/LT BLU) wire of the sensor's 3-wire connector.

The BLK/LT BLU wire connects to terminal 2 of the connector. As we did in TEST 2, we'll do a simple multimeter voltage check to confirm that Ground is present at terminal 2.

IMPORTANT: Never apply battery voltage to this wire under any circumstance. Doing so will permanently damage the PCM. The multimeter voltage test I'm outlining below is a safe, effective way to verify Ground.

Let's confirm the Ground path:

1. 1

   Unplug the CMP sensor from its connector.

2. 2

   Set your multimeter to measure DC Voltage.

3. 3

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

4. 4

   Use the black lead to probe terminal 2 of the sensor connector.
   
   NOTE: Confirm that terminal 2 actually connects to the BLK/LT BLU wire of the connector.

5. 5

   Turn the key to the ON (RUN) position, but don't crank the engine.

6. 6

   Your multimeter should show a reading of 10 to 12 Volts.

Here's what it all means:

CASE 1: Multimeter reads 10 to 12 Volts DC. That's perfect. It confirms the PCM is supplying a proper Ground path.

If you've already confirmed the CMP sensor has power (TEST 2) and isn't outputting a signal (TEST 1), and now you've verified Ground as well —the sensor itself is bad and the cause of P0340 and needs to be replaced.

CASE 2: You didn't see 10 to 12 Volts on your multimeter. Double-check your test setup and try again.

If Ground is still missing, the CMP sensor can't work. The most likely issue is an open or damaged section of the BLK/LT BLU wire somewhere between the sensor connector and the PCM connector.

Your next step is to troubleshoot and solve the issue causing this missing Ground to get the CMP sensor back to work and resolve code P0340.

More 2.4L Chrysler, Dodge, And Plymouth Minivan Tutorials

You can find a complete list of 2.4L Chrysler, Dodge, and Plymouth minivan tutorials in this index:

• 2.4L Chrysler, Dodge, And Plymouth Minivan Index Of Articles.

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

• Testing Engine Compression (1996-2007 2.4L Caravan, Grand Caravan, Voyager, Grand Voyager).
• How To Test For A Blown Head Gasket (1996-2007 2.4L Caravan, Grand Caravan, Voyager, Grand Voyager).
• How To Find Out If The Catalytic Converter Is Bad (1996-2007 2.4L Caravan, Grand Caravan, Voyager, Grand Voyager).
• How To Test The Fuel Injectors (1998-2000 2.4L Caravan And Voyager).