How To Test The CKP Sensor (1990-1993 3.3L V6 Chrysler, Dodge, And Plymouth Minivan)

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

If your CKP sensor isn't generating a signal, the next step is to check whether the PCM is supplying the required 8-volt power feed.

This voltage should appear at terminal #1 of the CKP sensor connector —the wire that connects to this terminal is an orange (ORG) wire.

We'll do a quick voltage check with our multimeter and the key in the RUN position (engine off) to see if the ORG wire is delivering power from the PCM.

Here's the process:

1. 1

   Disconnect the CKP sensor from its pigtail connector.

2. 2

   Place the black multimeter lead on the battery's negative (-) terminal.

3. 3

   Turn the ignition key to ON, but don't crank the engine.

4. 4

   Set your meter to Volts DC.

5. 5

   Use the red multimeter lead to probe terminal #1 at the connector.
   
   NOTE: Confirm that this terminal connects to the ORG wire.

6. 6

   The voltage reading should be around 7.5 to 8 Volts.

Let's see what your test result means:

CASE 1: 7.5 to 8 Volts confirmed. That tells you the PCM is delivering power to the CKP sensor —and that's good news.

Now you'll want to check if the sensor has a solid Ground connection. Head to: TEST 3: Making Sure The CKP Sensor Is Getting Ground.

CASE 2: No voltage detected. Check your multimeter setup, leads, and test point.

If the voltage still isn't present, the most likely issue is a break in the ORG wire somewhere between the PCM and the connector.

Your next step is to repair that open to restore the CKP sensor's functionality.

TEST 3: Making Sure The CKP Sensor Is Getting Ground

If you've completed the first two tests, you've confirmed the following:

• TEST 1: The CKP sensor isn't producing the expected ON/OFF voltage signal.
• TEST 2: The sensor is receiving its 8 Volt reference from the PCM.

The next thing to verify is whether the sensor has a proper Ground through the black with light blue stripe (BLK/LT BLU) wire at the connector.

The BLK/LT BLU wire runs to terminal 2 on the sensor —see the connector pinout diagram above.

IMPORTANT: This Ground comes directly from the PCM. Never connect this wire to battery power —doing so will damage the PCM. Instead, we'll do an easy and safe voltage test using our multimeter.

OK, let's get started checking the Ground circuit:

1. 1

   Disconnect the CKP sensor from its pigtail connector.

2. 2

   Place the red lead on the battery's positive (+) terminal.

3. 3

   Turn the key to ON (don't start the engine).

4. 4

   Set your meter to DC Volts.

5. 5

   Touch the black lead to terminal #2.
   
   NOTE: Confirm that the terminal actually connects to the BLK/LT BLU wire.

6. 6

   The multimeter should report a reading between 10 and 12 Volts if Ground is present in the BLK/LT BLU wire.

Time to interpret your test result:

CASE 1: You get 10–12 Volts. Excellent —that confirms the CKP sensor's Ground path is solid.

You can conclude the CKP sensor is bad and needs to be replaced if you have:

• Confirmed the CKP sensor isn't producing an ON/OFF voltage signal (TEST 1).
• Confirmed the sensor is receiving 8 Volts from the PCM (TEST 2).
• Confirmed the sensor is receiving Ground (this test section).

Check out this step next: Installing The CKP Sensor: Air Gap Clearance.

CASE 2: No voltage. Recheck your test connections and retest.

If there's still no reading, the Ground circuit likely has open-circuit problem —meaning the BLK/LT BLU wire has break somewhere between the sensor connector and the PCM connector. Without Ground, the sensor can't function.

You'll need to track down and fix the open in the BLK/LT BLU wire to get the CKP sensor working again.

Installing The CKP Sensor: Setting The Correct Air Gap

To operate correctly —and to prevent contact with the flywheel— the CKP sensor must maintain a specific air gap of roughly 0.020 inches (0.5 mm). This distance ensures the sensor can read the slots in the flywheel without getting struck by it.

This gap is established using a paper spacer and if you're installing a new sensor, that spacer should already be attached to its tip (most if not all new CKP sensor will come with it).

That spacer should never be removed since it guarantees the sensor's air gap as you're bolting it and securing it in place.

If you install the CKP sensor without one, the sensor may end up too far away or too close to the flywheel.

• If it's too far from the flywheel, it won't generate its signal.
• If it touches the flywheel, the spinning flywheel will smack the sensor on startup —destroying it instantly.

If you're reinstalling the same old sensor and the spacer is gone (which happens because the flywheel tends to rub it off), you can either buy one or make one using an index card (I've done this many times).

Cut out some round pieces, stack them up, and glue them until they measure exactly 0.020 inches thick. That'll restore the gap and ensure a safe install.

You can buy a replacement spacer online here:

• Walker Products 235-1378 CKP Sensor Spacer (at: amazon.com).

More 3.3L V6 Chrysler, Dodge, And Plymouth Minivan Tutorials

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