TEST 2: Testing The CKP Sensor's Output With A Multimeter
The crankshaft position sensor creates an AC voltage signal when the engine is cranking or running.
We can verify the CKP sensor signal in one of several ways. One of them is with a multimeter in AC Volts mode (that's how we'll test it in this section).
If the CKP sensor is good, it should produce an AC voltage as long as you're cranking the engine.
If the CKP sensor is bad, your multimeter will not report an AC voltage as you're cranking the engine.
As mentioned before, what complicates the CKP sensor's performance test is its location. The workaround uses a pigtail connector (like the one in the image above).
You can buy the CKP sensor pigtail connector at your local auto parts store or online here: ACDelco GM Original Equipment PT2437 Pigtail (at: amazon.com).
IMPORTANT: The battery must be fully charged to get the most accurate result from this test.
These are the test steps:
- 1
Disconnect the CKP sensor from its electrical connector.
LOCATION: The CKP sensor's connector is located on the right side of the intake manifold (near fuel injector #1). - 2
Connect the pigtail connector to the CKP sensor (the one you bought online or at your local auto parts store).
- 3
Place your multimeter in Volts AC mode.
- 4
Connect one of the multimeter test leads to one of the pigtail connector's wires.
It doesn't matter which multimeter test lead (red or black) you connect to this wire. - 5
Connect the other multimeter test lead to the other pigtail connector's wire.
- 6
Have a helper crank the engine as you observe the multimeter.
CAUTION: Be careful and stay alert as the engine is cranking. - 7
The multimeter should report an AC voltage that will oscillate somewhere around 0.4 to 1.2 Volts AC.
Let's take a look at what your test results mean:
CASE 1: The multimeter reported the indicated AC voltage. This test result confirms that the CKP sensor is functioning correctly.
CASE 2: The multimeter reported 0 AC voltage. This test result confirms that the crankshaft position sensor is bad and needs replacement.
More 4.2L Chevrolet TrailBlazer (GMC Envoy) Test Tutorials
If this tutorial was helpful, be sure and take a look at all of the 4.2L Chevrolet TrailBlazer and GMC Envoy test tutorials in this index:
Here's a sample of the tutorials you'll find there:
- How To Test For A Blown Head Gasket (2002-2009 4.2L Chevrolet TrailBlazer).
- How Often Should I Replace The Spark Plugs? (2002-2009 4.2L Chevrolet TrailBlazer).
- How To Test Engine Compression (2002-2009 4.2L Chevrolet TrailBlazer).
- Electronic Throttle Body Tests (2002-2007 4.2L Chevrolet TrailBlazer).
If this info saved the day, buy me a beer!
