How To Test The CMP Sensor (1996-1998 1.5L Mazda Protege)

TEST 2: Making Sure The CMP Sensor Is Getting Ground

Now that you've made sure that the camshaft position (CMP) sensor is getting power, the next step is to make sure that it's getting Ground.

On the 1996 1.5L Mazda Protege (with Federal Emissions), Ground is supplied to the CMP sensor by the black with purple stripe (BLK/PPL) wire of the distributor's 7-wire connector.

On the 1997-1998 1.5L Mazda Protege, Ground is supplied to the CMP sensor by the black with red stripe (BLK/RED) wire of the distributor's 7-wire connector.

In the photo above, the terminal that connects to the CMP sensor's Ground wire is the one I've labeled with the letter A.

NOTE: This Ground is a chassis Ground and is provided at all times.

These are the test steps:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Disconnect the 7-wire connector from the distributor.

3. 3

   Connect the red multimeter test lead directly on the battery positive (+) terminal.

4. 4

   Gently probe the female terminal labeled with the letter A with the black multimeter test lead.

5. 5

   Your multimeter should register 10 to 12 Volts DC.
   
   There's no need to turn the key to ON position since this is a chassis Ground and is available at all times.

Let's examine your test result:

CASE 1: Your multimeter registered 10 to 12 Volts. This is the correct test result and confirms that the CMP sensor is getting Ground.

The next step is to make sure that the CMP sensor is producing a CMP signal. For this test go to: TEST 3: Testing The CMP Signal With A Multimeter.

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Without Ground the CMP sensor will not function.

Your next step is to repair this Ground wire and retest.

TEST 3: Testing The CMP Signal With A Multimeter

As you're probably already aware, your Mazda Protege's camshaft position (CMP) sensor produces a signal that the fuel injection computer uses to activate the ignition control module.

Without the CMP signal, your Mazda Protege will not start due to a lack of spark.

Now that you've made sure that the CMP sensor is receiving power and Ground, we're gonna' make sure the CMP sensor is producing a signal.

NOTE: The distributor must remain connected to its 7-wire electrical connector for this test to function. You'll need to use a back probe on the connector or a wire piercing probe on the CMP signal wire. You can see an example of this tool here: Wire Piercing Probe.

IMPORTANT: This test requires that you turn the engine by hand (with the appropriate tools). Don't use the starter motor to test for the CMP signal.

OK, these are the test steps:

1. 1

   Reconnect the distributor to its 7-wire connector.

2. 2

   Connect the red multimeter test lead to the violet with green stripe (VIO/GRN) wire of the distributor's 7-wire connector.
   
   The VIO/GRN wire connects to the female terminal labeled with the letter C in the photo above.
   
   IMPORTANT: The distributor must remain connected to its electrical connector.

3. 3

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

4. 4

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

5. 5

   Turn the engine by hand using the appropriate tools when you have everything set up.
   
   You can accomplish this by turning the crankshaft pulley with a socket and ratchet.

6. 6

   The multimeter should register an ON/OFF voltage of 5 Volts DC as you turn the engine by hand.
   
   OFF is when the voltage is 0 Volts and ON is when the voltage is 5 Volts.

Let's analyze your test result:

CASE 1: The multimeter registered the indicated ON/OFF voltage pulse as you turned the crankshaft pulley. This is the correct test result and confirms that the CMP sensor is functioning correctly (not defective).

CASE 2: The multimeter DID NOT register the indicated ON/OFF voltage pulse as you turned the crankshaft pulley. This test result tells you that the camshaft position sensor is not producing its CMP signal.

You can conclude that the CMP sensor is bad if you have confirmed that:

• The ignition coil does not spark.
• The camshaft position sensor is getting 10 to 12 Volts (TEST 1).
• The camshaft position sensor has Ground (TEST 2).
• The camshaft position sensor is not creating its ON/OFF voltage signal (this test section).

The camshaft position sensor is not sold separately. You'll need to replace the distributor.

More 1.5L Mazda Protege Tutorials

You can find a complete list of 1.5L Mazda Protege tutorials in this index:

• Mazda 1.5L Index Of Articles.

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

• P0122 -What Does It Mean? (1996-1998 1.5L Mazda Protege).
• How To Test The TPS (1996-1998 1.5L Mazda Protege).
• How To Test The MAF Sensor (1996-1998 1.5L Mazda Protege).
• How To Test Engine Compression (1995-1998 1.5L Mazda Protege).