TEST 2: Making Sure The CKP Sensor Is Getting Power
In this test section, we're gonna' make sure that the CKP sensor is receiving 8 Volts, since without them, it won't produce its CKP signal.
The wire that supplies these 8 Volts to the CKP sensor is the orange (ORG) wire of engine wiring harness connector.
We'll do a simple multimeter voltage test to find out if they are present in the wire or not.
These are the test steps:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the crankshaft position sensor from its connector.
- 3
With the red multimeter test lead, gently probe the terminal that connects to the orange (ORG) wire of the engine wiring harness connector.
- 4
Connect the black multimeter test lead to the battery negative (-) terminal.
- 5
Turn the key to the ON position but don't crank the engine.
- 6
Your multimeter should register 7.5 to 8 Volts DC.
OK, let's analyze your test result:
CASE 1: The multimeter registered 7.5 to 8 Volts DC. This is the correct test result.
There is still one more test to do and that is to make sure the CKP sensor is getting Ground. Go to: TEST 3: Making Sure The CKP Sensor Is Getting Ground.
CASE 2: The multimeter DID NOT register the indicated voltage. Recheck your connections and try the test again.
If the multimeter still does not register 8 Volts, then you now have confirmed that the lack of power is the reason why the CKP sensor is not working.
The most likely cause of this missing voltage is an open-circuit problem somewhere on the ORG wire.
TEST 3: Making Sure The CKP Sensor Is Getting Ground
In this test step, you're going to verify that the crankshaft position sensor is getting Ground.
The wire that feeds the CKP sensor with Ground is the black with light blue stripe (BLK/LT BLU) wire of the engine wiring harness connector.
IMPORTANT: You got to be very careful not to short this wire to battery voltage, or you run the risk of damaging the PCM. The multimeter voltage test I'm suggesting in the test instructions is a safe way to test for the presence of Ground in the wire.
Alright, this is what you'll need to do:
- 1
Place your multimeter in Volts DC mode.
- 2
Disconnect the crankshaft position sensor from its connector.
- 3
With the black multimeter test lead, gently probe the female terminal that connects to the BLK/LT BLU wire.
- 4
Connect the red multimeter test lead to the battery positive (-) terminal.
- 5
Have you helper turn the key to the ON position but don't crank the engine.
- 6
Your multimeter should register 10 to 12 Volts DC.
Let's interpret your test result:
CASE 1: The multimeter registered 10 to 12 Volts DC. This is the correct and expected test result and it confirms that the CKP sensor is getting Ground.
This results confirms that the crankshaft position (CKP) sensor is bad and needs to be replaced only if you have:
- Confirmed in TEST 1 that the CKP sensor is not creating its ON/OFF voltage signal.
- Confirmed in TEST 2 that the CKP sensor is being fed with power (8 Volts).
- In this test step, you have confirmed that it's getting Ground.
CASE 2: The multimeter DID NOT register 10 to 12 Volts DC. Recheck your connections and try the test again.
If the multimeter still does not register 10 to 12 Volts, then this result lets you know that the CKP is not receiving Ground. The most likely cause of this missing Ground is an open-circuit problem somewhere on the BLK/LT BLU wire.
More 4.0L Jeep Cherokee Tutorials
You can find a complete list of diagnostic tutorials and wiring diagrams for the 4.0L Jeep Cherokee here:
Here's a sample of the tutorials you'll find in the index:
- Ignition System Wiring Diagram (1993-1995 4.0L Jeep Cherokee)
- How To Test For A Blown Head Gasket (1993-2001 4.0L Jeep Cherokee)
- How To Test The Crankshaft Position Sensor Jeep 4.0L (1997-1998 4.0L Jeep Cherokee)
- How To Test The Front O2 Sensor Heater (1996 4.0L Jeep Cherokee)
- How To Do An Engine Compression Test (1993-2001 4.0L Jeep Cherokee)
If this info saved the day, buy me a beer!
