How To Test The CMP Sensor -P0340 (1996-2000 2.4L Dodge And Plymouth Minivan)

TEST 2: Making Sure The CMP Sensor Is Getting 8 Volts

In this next step, we'll check that the orange (ORG) wire is delivering 8 Volts to the CMP sensor like it's supposed to.

This wire connects to pin 1 on the CMP sensor's harness connector, as shown in the diagram above.

The 8 Volt supply comes directly from the PCM (Powertrain Control Module), and you'll test for it using a multimeter with the ignition key in the ON (RUN) position —engine off.

Let's get started:

1. 1

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

2. 2

   Set your multimeter to DC Volts mode.

3. 3

   Attach the black multimeter lead to the battery's negative (-) terminal.

4. 4

   Touch the red multimeter lead to the terminal marked as pin 1 on the connector.
   
   NOTE: Check that terminal 1 corresponds to the ORG wire.

5. 5

   Have a helper switch the key to the RUN position. No need to start the engine.

6. 6

   You should see a voltage reading between 7 and 8 Volts.

Here's how to interpret your result:

CASE 1: You got a reading of 7 to 8 Volts DC. Perfect. This confirms the CMP sensor is receiving the power it needs to function.

Now that power is confirmed, your next step is to verify its Ground connection. Continue to: TEST 3: Making Sure The CMP Sensor Is Getting Ground.

CASE 2: You did NOT get a voltage reading between 7 and 8 Volts. Double-check your multimeter setup and connection points, then retest.

If the voltage is still missing, the CMP sensor itself isn't the issue —without power, it can't generate a signal.

The most likely culprit is an open-circuit in the ORG wire somewhere between the CMP connector and the PCM.

TEST 3: Making Sure The CMP Sensor Is Getting Ground

Here's what you've verified so far:

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

Now it's time to make sure the CMP sensor is getting a reliable Ground through the black with light blue stripe (BLK/LT BLU) wire.

The BLK/LT BLU wire connects to terminal 2 of the CMP sensor's 3-wire connector.

IMPORTANT: Never apply 12 Volts directly to this wire. Doing so will fry the PCM. The voltage test described below is safe and effective —it checks for Ground without risking damage to any components.

Here's how to check the Ground circuit:

1. 1

   Unplug the CMP sensor.

2. 2

   Switch your multimeter to Volts DC mode.

3. 3

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

4. 4

   Probe terminal number 2 on the connector with the black multimeter lead.
   
   NOTE: Check that terminal 2 connects to the BLK/LT BLU wire.

5. 5

   Have your helper turn the key to the RUN position, but don't start the engine.

6. 6

   Your multimeter should read 10 to 12 Volts.

Let's break down what your results mean:

CASE 1: You saw 10 to 12 Volts DC on the multimeter. This confirms that the PCM is supplying a solid Ground path to the CMP sensor.

At this point, if the sensor isn't producing an ON/OFF signal (TEST 1), even though it's getting both power (TEST 2) and Ground, it's safe to say the CMP sensor is faulty and the root cause of code P0340.

CASE 2: You didn't get a 10 to 12 Volt reading. Recheck your test connections and try again.

If there's still no voltage, then the Ground path is missing. Without a proper Ground, the CMP sensor can't operate, and the PCM will usually respond by setting P0340.

The most likely cause is an open-circuit (or break) in the BLK/LT BLU wire somewhere between the connector and the fuel injection computer.

More 2.4L Chrysler, Dodge, And Plymouth Minivan Tutorials

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

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