How To Test The CMP Sensor (2001-2003 3.3L V6 Chrysler And Dodge Minivan)

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

Since the CMP sensor isn't generating an ON/OFF voltage pulse —we now need to confirm that it's being powered by the PCM with 8 Volts DC.

The sensor's voltage feed enters at terminal #1, which connects to the brown with pink stripe (BRN/PNK) wire, and we'll check it with a multimeter and the ignition key in the RUN position (but engine OFF).

It only takes a minute, but if the voltage isn't there, the sensor can't work —so this step is a must before moving on to anything else.

OK, let's get this show on the road:

1. 1

   Disconnect the CMP sensor.

2. 2

   Ground the black lead directly on the battery's negative (-) terminal.

3. 3

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

4. 4

   Set your multimeter to DC Volts.

5. 5

   Gently probe the terminal labeled 1 using the red multimeter test lead.
   
   Confirm that terminal 1 actually connects to the BRN/PNK wire.

6. 6

   You should see a reading around 7.5 to 8 Volts DC.

Let's see what this result is telling us:

CASE 1: 7.5 to 8 Volts measured. Perfect —you've confirmed that the PCM is supplying power to the CMP sensor.

The next step is to make sure the CMP sensor is getting Ground. Head over to: TEST 3: Making Sure The CMP Sensor Is Getting Ground.

CASE 2: No voltage at the sensor. Check your test connections and repeat the test.

If there's still no 8 Volts, then the problem likely lies in the BRN/PNK wire between the PCM and the sensor connector —a break (open-circuit) in the wire is usually to blame.

Your next step is to troubleshoot the cause of this missing power supply and restore it to the BRN/PNK wire to resolve the CMP sensor problem.

TEST 3: Making Sure The CMP Sensor Is Getting Ground

In the previous two tests, you've confirmed:

• The CMP sensor isn't producing its expected ON/OFF signal (TEST 1).
• It's getting fed 8 Volts (TEST 2).

The final thing to check is the Ground wire, which is the dark blue with dark green stripe (DK BLU/DK GRN) wire of the CMP sensor connector.

The DK BLU/DK GRN wire connects to the terminal I've labeled with the number 2 in the illustration of the connector pinout above.

IMPORTANT: Never jumper this wire to battery power —that's a guaranteed way to deep fry the PCM. To check for Ground in this circuit, we'll do an easy and safe voltage test with the multimeter.

This is what you need to do:

1. 1

   Disconnect the CMP sensor.

2. 2

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

3. 3

   Switch the key to RUN but don't crank the engine.

4. 4

   Set the meter to Volts DC.

5. 5

   Probe terminal #2 with the black multimeter test lead.
   
   Double-check that terminal 2 connects to the DK BLU/DK GRN) wire.

6. 6

   Your multimeter should show around 10 to 12 Volts if the CMP sensor has a solid Ground path.

Let's see what this result is pointing to:

CASE 1: 10 to 12 Volts shows up on the multimeter. That's the confirmation we need —Ground is good.

If the CMP sensor has power (TEST 2) but didn't produce an ON/OFF signal (TEST 1), then it has failed internally and must be replaced.

Since you'll be replacing the CMP sensor, see: Installing The CMP Sensor: Air Gap Clearance.

CASE 2: 0 Volts or no reading at all. Double-check your test connections and try again.

If you still don't see voltage, the Ground wire has an open circuit problem. Without that Ground, the sensor won't work, and the fault lies in the wiring, not the sensor itself.

Your next step is to troubleshoot the cause of this missing Ground and restore it to the DK BLU/DK GRN wire to resolve the CMP sensor problem.

Installing The CMP Sensor: Air Gap Clearance

The CMP sensor requires a specific air gap —approximately 0.020 inches (0.5 mm)— from the camshaft gear to function correctly.

This gap is established using a paper spacer attached to the CMP sensor's tip during installation.

A new CMP sensor will already have it installed on its tip and it's important not to remove this spacer, as it ensures the sensor maintains the correct distance once it's bolted to the timing cover.

Resist the urge to peel it off —doing so could leave the sensor too close to the camshaft gear, which will get destroyed the moment you crank the engine.

Should the original spacer be missing, maybe because you're reusing the old sensor (the cam gear usually trims it off), you can make a replacement using index cards.

Cut small circles, stack and glue them together until they reach the required thickness of 0.020 inches (0.5 mm). This homemade spacer will maintain the proper clearance and let you tighten the sensor bolt correctly.

If you don't want to mess with making one, you can buy a replacement spacer online here:

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

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

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• 3.3L V6 Chrysler, Dodge, And Plymouth Minivan Index Of Articles.

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