TEST 2: Making Sure The CKP Sensor Is Getting 5 Volts
A reliable voltage supply is essential for the CKP sensor to deliver precise and consistent readings. This voltage supply is typically regulated to ensure it remains constant regardless of fluctuations in the vehicle's electrical system or operating conditions.
In the case of our CKP sensor, the regulated voltage supply is set to 5 volts. The wire that delivers these 5 Volts to the CKP sensor is the purple with white stripe (PPL/WHT) wire.
The PPL/WHT wire is the one that connects to the female terminal of the connector labeled with the letter C in the illustration above.
We'll perform a simple multimeter voltage test to check for the presence of these 5 Volts in the PPL/WHT wire with the key on but engine off.
This is what you'll need to do:
- 1
Set your multimeter to Volts DC mode.
- 2
Connect the black multimeter test lead to the battery negative (-) post or a clean and unpainted metal spot on the engine.
- 3
With the red multimeter test lead, probe the female terminal identified with the letter C of the CKP sensor connector.
The PPL/WHT wire should connect to terminal C. - 4
When everything is set up, have your helper turn the key to the RUN position.
- 5
Your multimeter should register 4.5 to 5 Volts.
OK, let's interpret your test result:
CASE 1: The multimeter registered 4.5 to 5 Volts DC when the key was turned On. This is the correct test result and confirms the PCM is providing power to the CKP sensor.
There is 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: TEST 3: Making Sure The CKP Sensor Is Getting Ground.
CASE 2: The multimeter DID NOT register the indicated voltage when the key was turned On. Recheck your connections and try the test again.
If the multimeter still does not register 4.5 to 5 Volts, the issue causing the CKP sensor malfunction is a lack of power from the PCM. The most likely cause of these missing 5 Volts is an open-circuit issue in the wire between the CKP sensor connector and the PCM connector.
TEST 3: Making Sure The CKP Sensor Is Getting Ground
Like many sensors in automotive systems, the CKP sensor requires a complete electrical circuit to function properly. This circuit consists of a power supply (such as a 5-volt reference voltage you just confirmed in TEST 2) and a Ground connection.
The Ground connection serves as the return path for 5 Volts and is essential for completing the circuit and allowing the sensor to operate.
In the case of our CKP sensor, Ground is provided by the PCM and is called 'low reference' in most of the repair/service literature.
The wire that delivers this 'low reference' signal to the CKP sensor is the grey with black stripe (GRY/BLK) wire, which connects to the female terminal of the connector labeled with the letter B in the illustration above.
We'll perform a simple multimeter voltage test to check for the presence of Ground in the GRY/BLK wire with the key on but engine off.
IMPORTANT: Be careful not to short this sensor Ground wire to battery voltage, or you run the risk of damaging the PCM. The multimeter voltage test described in the test steps is a safe way to check for the presence of Ground in the circuit.
These are the test steps:
- 1
Set your multimeter to Volts DC mode.
- 2
Connect the red multimeter test lead to the battery positive (+) post.
- 3
With the black multimeter test lead, probe the female terminal identified with the letter B of the CKP sensor connector.
The GRY/BLK wire should connect to terminal B. - 4
When everything is set up, have your helper turn the key to the RUN position.
- 5
Your multimeter should register 10 to 12 Volts if Ground is present in the circuit.
Let's find out what your test results mean:
CASE 1: The multimeter registered 10 to 12 Volts DC when the key was turned On. Then the CKP sensor is getting a good Ground.
You can conclude that the CKP sensor 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 the indicated voltage when the key was turned On. Recheck your connections and try the test again.
If the multimeter still does not register 10 to 12 Volts, the issue causing the CKP sensor malfunction is a lack of Ground from the PCM. The most likely cause of this missing Ground is an open-circuit issue in the wire between the CKP sensor connector and the PCM connector.
More Chevy Express/GMC Savana Articles And Tutorials
You can find a complete list of articles and diagnostic tutorials for the V8 Chevy Express and GMC Savana here:
Here's a sample of the tutorials you'll find in the index:
- How To Test For The Fuel Pump (2008-2013 V8 Chevy Express, GMC Savana).
- How To Test For A Blown Head Gasket (2003-2013 V8 Chevy Express, GMC Savana).
- How To Diagnose An Engine Cranks But Does Not Start Problem (2003-2007 V8 Chevy Express, GMC Savana).
- How Can I Tell If The Automatic Transmission Is Bad? (2003-2013 Chevrolet Express, GMC Savana).
If this info saved the day, buy me a beer!
