How To Test The CMP Sensor -P0340 (2003-2007 2.4L Chrysler And Dodge Minivan)

TEST 2: Confirming The CMP Sensor Is Getting 5 Volts

Next up, let's make sure the pink with yellow stripe (PNK/YEL) wire is delivering the required 5 Volts to the CMP sensor —just like it's supposed to.

This wire runs to pin 1 of the CMP sensor's 3-wire harness connector. You can find its location in the connector diagram above.

The 5 Volt supply comes directly from the PCM (Powertrain Control Module). We're going to use a multimeter to check for it with the ignition key in the ON (RUN) position —but with the engine off.

Here's how to run the voltage test:

1. 1

   Disconnect the CMP sensor from its connector.

2. 2

   Set your multimeter to Volts DC mode.

3. 3

   Connect the black multimeter test lead to the negative (-) terminal on the battery.

4. 4

   Carefully probe terminal 1 of the connector with the red multimeter test lead.
   
   NOTE: Double-check that terminal 1 actually connects to the PNK/YEL wire of the connector.

5. 5

   Have your helper turn the key to the ON position (don't crank the engine).

6. 6

   The multimeter should read between 4.5 and 5 Volts.

Now let's look at what your results mean:

CASE 1: Multimeter shows 4.5 to 5 Volts. Perfect. That confirms the PCM is sending the required power to the CMP sensor so it can generate its signal.

With power verified, your next move is to test the Ground circuit. Head over to: TEST 3: Making Sure The CMP Sensor Is Getting Ground.

CASE 2: No voltage detected. Check your connections and retest.

If you're still not seeing 5 Volts, the CMP sensor isn't getting the power it needs —and without power, it won't produce its ON/OFF signal and set code P0340.

In most cases, the issue is an open or broken section of the PNK/YEL wire between the sensor and the PCM —not the sensor itself. Fixing that wiring problem is key to restoring signal output and clearing P0340.

TEST 3: Making Sure The CMP Sensor Is Getting Ground

At this point in your CMP sensor diagnosis, you've confirmed two things:

• The sensor is not outputting an ON/OFF voltage signal (TEST 1).
• It's receiving the proper 5 Volt power supply from the PCM (TEST 2).

Now it's time to verify that the sensor has a solid Ground connection through the dark blue with dark green stripe (DK BLU/DK GRN) wire on the connector.

This wire connects to terminal 2 of the sensor's 3-wire connector. Just like we did for the power test, we'll use a multimeter to confirm that Ground is present at terminal 2.

IMPORTANT: Never apply battery voltage to this wire —doing so will deep fry the PCM. The method below is safe and reliable, and it'll tell you whether the PCM is properly Grounding the sensor.

Here's how to test for Ground:

1. 1

   Disconnect the CMP sensor so you can access the connector pins.

2. 2

   Set your multimeter to DC Volts mode.

3. 3

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

4. 4

   Probe terminal 2 of the sensor connector with the black test lead.
   
   NOTE: Double-check that terminal 2 actually connects to the DK BLU/DK GRN wire.

5. 5

   Turn the ignition key to the ON (RUN) position, without cranking the engine.

6. 6

   Your multimeter should show a reading between 10 and 12 Volts.

Here's how to interpret the result:

CASE 1: Multimeter reads 10 to 12 Volts. Perfect. This confirms that the PCM is providing a clean and working Ground path to the CMP sensor.

So if you've already confirmed power (TEST 2) and the sensor is still not producing a signal (TEST 1), and now Ground checks out too —the CMP sensor itself is toast. That's what's triggering code P0340, and it needs to be replaced.

CASE 2: No voltage reading on the meter. Go back and double-check your test connections.

If the reading is still zero, the CMP sensor isn't getting Ground, which means it can't work. The most likely cause is an open-circuit problem in the DK BLU/DK GRN wire between the sensor and the PCM.

Your next step is to track down and repair that missing Ground to get the CMP sensor back online and clear out P0340.

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