CKP Sensor Test -No Spark No Start Tests (GM 4.8L, 5.3L, 6.0L)

CKP TEST 2: Making Sure The CKP Sensor Is Getting 12 Volts

So far, in TEST 1, you have confirmed that the CKP sensor is not creating a crank signal.

So, in this test step, you're gonna verify that the CKP sensor is getting power.

Since the CKP sensor on your GM vehicle is a Hall Effect type sensor, it needs an external power source to create its signal. This power comes in the form of 12 Volts.

This is what you'll need to do:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Connect the black multimeter test lead to the battery negative (-) post or a clean and unpainted metal spot on the engine.

3. 3

   Disconnect the CKP sensor from its electrical connector.

4. 4

   With the red multimeter test lead, probe the female terminal that connects to the wire identified with the letter C.

5. 5

   When everything is set up, have your helper turn the key to the RUN position.

6. 6

   Your multimeter should register 10 to 12 Volts.

OK, let's interpret the multimeter test results you just obtained:

CASE 1: The multimeter registered 12 Volts DC when the key was turned On. This is the correct test result and confirms the CKP sensor is getting power (12 Volts) from the PCM.

There's still one more test to do, before we can condemn the CKP sensor as bad, and that is to test the Ground circuit. Go to CKP TEST 3: Making Sure The CKP Sensor Is Getting Ground.

CASE 2: The multimeter DID NOT register 12 Volts DC when the key was turned On. Recheck your connections and try the test again.

If the multimeter still does not register 12 Volts, then this result lets you know that the reason that the CKP sensor did not produce a signal, in TEST 1, is because the crankshaft position (CKP) sensor is not getting power. You have now eliminated the CKP sensor as the cause of the no-start condition.

Solving the issue that is causing these missing 12 Volts will solve the no-start condition of your 4.8L, 5.3L, 6.0L GM vehicle.

CKP TEST 3: Making Sure The CKP Sensor Is Getting Ground

So far you have confirmed that the CKP sensor is not creating a signal and that it's getting fed with 12 Volts.

In this test step, you're going to verify that the crankshaft position sensor is getting Ground. As mentioned earlier, the Ground path is completed inside the PCM.

IMPORTANT: You got to be very careful not to short this wire to battery voltage, or you run the risk of damaging the PCM. Also, do not use a test light to verify this voltage, use a multimeter.

Let's get started:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

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

3. 3

   Disconnect the CKP sensor from its electrical connector (if it isn't already).

4. 4

   With the black multimeter test lead, probe the female terminal that connects to the wire identified with the letter B.

5. 5

   When everything is set up, have your helper turn the key to the RUN position.

6. 6

   Your multimeter should register 10 to 12 Volts if Ground is present in the circuit.

Choose from the CASES below that best match your specific results:

CASE 1: The multimeter registered 10 to 12 Volts DC when the key was turned On. This is the correct test result and confirms the CKP sensor is getting Ground from the PCM.

You can conclude that the CKP is bad and in need of replacement if you have:

• Confirmed that the CKP sensor is not generating an ON/OFF voltage (TEST 1).
• Confirmed that the sensor is getting 4.5 to 5 Volts (TEST 2).
• Confirmed, in this section, that the sensor is getting Ground.

CASE 2: The multimeter DID NOT register 10 to 12 Volts DC when the key was turned On. Recheck your connections and try the test again.

If the multimeter still does not register 12 Volts, then this result lets you know that the CKP does not have a good sensor Ground. You have now eliminated the CKP sensor as the cause of the no-start condition, since without this Ground, the CKP sensor will not work.

Related Test Articles

You can find a complete list of tutorial in this index:

• GM 4.8L, 5.3L, 6.0L Index of Articles

At easyautodiagnostics.com, you can find these tutorials:

• How To Test The MAF Sensor (at: easyautodiagnostics.com).
• How To Test The COP Coils (GM 4.8L, 5.3L, 6.0L, 8.1L) (at: easyautodiagnostics.com).
• How To Test The Starter Motor (on car) (at: easyautodiagnostics.com).
• How To Bench Test The Starter Motor (at: easyautodiagnostics.com).