In this tutorial I'll show you how to test the crankshaft position (CKP) sensor with a simple multimeter and in a step-by-step way.
You'll be able to easily find out if it's bad and causing your 4.0L Jeep Cherokee no-start problem.
Contents of this tutorial:
- Important Tips And Suggestions.
- Where To Buy The Crankshaft Position Sensor And Save.
- Circuit Descriptions Of The Crankshaft Position Sensor.
- TEST 1: Testing The CKP Signal With A Multimeter.
- TEST 2: Making Sure The CKP Sensor Is Getting 5 Volts.
- TEST 3: Making Sure The CKP Sensor Is Getting Ground.
- More 4.0L Jeep Cherokee Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Sensor CKP (1997-1998 4.0L Jeep Cherokee) (at: autotecnico-online.com).
APPLIES TO: This tutorial, on testing the CKP sensor, applies to the following vehicles:
- 1997, 1998 4.0L Jeep Cherokee.
RELATED WIRING DIAGRAMS:
- How To Test The Crankshaft Position Sensor (1993-1995 4.0L Jeep Cherokee).
- How To Test The Crankshaft Position Sensor (1996 4.0L Jeep Cherokee).
Important Tips And Suggestions
TIP 1: The CKP sensor test is an on-car test -it should not be removed to test it.
TIP 2: It's important to manually turn the engine with a socket and wrench in TEST 1. Don't use the starter motor.
TIP 3: Test the spark plug wires for spark before testing the CKP sensor (if you haven't already).
If any of the spark plug wires are sparking, then the CKP sensor is OK and doing its job.
TIP 4: Take all necessary safety precautions. Think safety all of the time.
Where To Buy The Crankshaft Position Sensor And Save
The following links will help you to comparison shop for the CKP sensor of known automotive name-brands (Standard Motor Products, Dorman, OE Management) that fit the 1997-1998 4.0L Jeep Cherokee:
Not sure if the above crankshaft position sensor fits your particular 1997, 1998 4.0L Jeep Cherokee? Don't worry, once you get to the site, they'll make sure it fits by asking you the particulars of your vehicle. If it doesn't fit, they'll find you the right one.
Circuit Descriptions Of The Crankshaft Position Sensor
The crankshaft position sensor is a 3-wire Hall Effect sensor. Here's a brief description of the wires we'll be testing:
|1||Orange (ORG)||5 Volts|
|2||Brown With Yellow Stripe (BRN/YEL)||Sensor Ground|
|3||Gray With Black Stripe (GRY/BLK)||CKP Signal|
You can consult the following ignition system wiring diagram for more info:
TEST 1: Testing The CKP Signal With A Multimeter
A good crankshaft position (CKP) sensor produces an ON/OFF voltage signal that can easily be verified with a multimeter.
For our first test, we're gonna' connect a multimeter to the CKP signal wire and manually turn the engine.
If the CKP sensor is functioning, your multimeter will register an ON/OFF voltage signal.
ON is when the multimeter reads 5 Volts DC. OFF is when the multimeter reads 0 Volts.
The CKP signal wire is the gray with black stripe (GRY/BLK) wire of the CKP sensor's engine wiring harness connector.
NOTE: The CKP sensor must remain connected to its electrical connector for this test to work. You'll need to use a back probe on the connector or a wire piercing probe on the wire. You can see an example of this tool (and where to buy it) here: Wire Piercing Probe Review (Power Probe PWPPPPP01).
OK, let's get started:
Disable the ignition system by disconnecting the ignition coil.
This is an important safety precaution -do not proceed to the next step until you've done this.
Disable all of the fuel injectors.
This step is important also, since this will prevent the PCM from injecting fuel into the engine cylinders (if the CKP sensor is OK).
Locate the CKP sensor's connector.
Place the multimeter in Volts DC mode.
Connect the red multimeter test lead to the GRY/BLK wire of the engine wiring harness connector with an appropriate tool.
NOTE: The CKP sensor must remain connected to its electrical connector for this test to work.
Connect the black multimeter test lead to battery negative (-) terminal.
Turn the key to the ON position (but don't crank the engine). This will power up the crankshaft position sensor.
Have a helper turn the crankshaft pulley by hand in a clock-wise direction while you observe the multimeter.
NOTE: Do not use the starter motor to crank the engine, since this will defeat the accuracy of this test.
Your multimeter should show an ON/OFF voltage as you manually turn the crankshaft pulley.
OFF is when your multimeter reads 0 Volts and ON is when it reads 5 Volts.
The key to seeing this voltage change is to turn the crankshaft pulley slowly and steadily.
Alright, let's interpret your test results:
CASE 1: The multimeter registered the ON/OFF signal voltage. This is the correct and expected test result and it confirms that the crankshaft position sensor is working correctly.
CASE 2: The multimeter DID NOT register the ON/OFF signal voltage. This usually means that the CKP sensor is bad and that it needs to be replaced.
To be sure it's bad, the next step is to check that the crankshaft position sensor is getting 5 Volts DC. For this test go to: TEST 2: Making Sure The CKP Sensor Is Getting 5 Volts.