You can easily find out if the crankshaft position sensor is good or bad with a multimeter on your 4.0L Ford Ranger (Mazda B4000).
This tutorial will explain how you can do this with step-by-step instructions.
NOTE: You can find the 1991-1997 4.0L OHV Ford Explorer (Aerostar) CKP sensor test here:
- How To Test The CKP Sensor (1991-1997 4.0L Ford Explorer And Aerostar) (at: troubleshootmyvehicle.com).
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 4.0L OHV V6 Ford Ranger: 1991, 1992, 1993, 1994, 1995, 1996, 1997.
- 4.0L OHV V6 Mazda B4000: 1994, 1995, 1996, 1997, 1998, 1999, 2000.
OHV: Over Head Valve.
The 1998-2011 4.0L Ford Ranger (Mazda B4000) CKP test tutorial is here:
Important Tips And Suggestions
TIP 1: The CKP sensor is located right behind the crankshaft pulley since the CKP sensor's reluctor wheel is behind (and part of) the crank pulley.
TIP 2: The battery in your Ford Ranger (Mazda B4000) must be fully charged. This is important because you'll measure the CKP sensor's signal while cranking the engine. A low battery will cause the engine to crank slower than usual, and you're not gonna see a good CKP sensor signal result on your multimeter.
TIP 3: You'll need to jack up the vehicle to access the CKP sensor. After raising the vehicle, place it on jack stands. Do not trust the jack! Use safety glasses also. Be careful, use common sense, and think safety all of the time.
TIP 4: The first thing you should do before testing the CKP sensor is check for spark at all spark plug wires (high tension cables). Why? Well, if even just one spark plug cable has spark, this tells you that the CKP sensor is OK.
In other words, when the crankshaft position sensor goes bad, you'll get a no-spark no-start condition, so if you're getting spark, even if in just one cylinder, the CKP sensor is good, and this test will not help you.
TIP 5: This tutorial does not cover any remove and replace instructions for accessing or replacing the CKP sensor. You'll need a repair manual for them (or Google).
Symptoms Of A Bad CKP Sensor
The most obvious symptom of a bad crankshaft position sensor is an engine no-start problem.
The engine no-start issue only happens when the CKP sensor has failed completely.
What complicates things a bit is the fact that the CKP sensor can fail intermittently.
When this happens, the engine will start and run most of the time. But when the CKP sensor decides to stop functioning, the engine won't start.
Eventually, the CKP sensor functions again and allows the engine to start. These intermittent failures are the hardest to troubleshoot.
Where To Buy The CKP Sensor And Save
The crankshaft position sensor isn't an expensive component. The following links will help you to comparison shop and save a few bucks on known automotive brand CKP sensors:
Not sure if the CKP sensor fits your particular 4.0L Ford Ranger (Mazda B4000)? Don't worry, once you get to the site they'll make sure it fits by asking you the specifics of your particular Ford vehicle. If it doesn't fit, they'll find you the right CKP sensor.
Testing The CKP Sensor Signal With A Multimeter
The crankshaft position sensor is a variable reluctance sensor. In plain English, this means that it produces an AC voltage when the engine is cranking or running (and if it's functioning correctly).
To test it, you'll connect your multimeter test leads to the sensor connector's two wires.
Then you'll need a helper to crank the engine while observing the CKP sensor's AC voltage output.
If the CKP sensor is bad, it will not produce an AC voltage.
If the sensor is good, your multimeter should register a voltage between 0.5 to 1.2 Volts AC (as the engine cranks).
IMPORTANT: This test is done with the CKP sensor connected to its electrical connector.
CAUTION: The engine has to be cranked to test the CKP sensor's AC voltage output. Be careful and take all necessary safety precautions.
Let's get started:
- 1
Unplug the CKP sensor from its electrical connector.
You may need to remove some of the plastic wire loom protector and/or the black electrical tape that shields/protects the two wires of the CKP sensor. - 2
Connect the red multimeter test lead to one of the two wires of the connector.
IMPORTANT: Make sure your multimeter test leads DO NOT interfere with the crankshaft pulley or the serpentine drive belt, since you'll be cranking the engine in one of the following steps. - 3
Connect the black multimeter test lead to the remaining wire of the connector
IMPORTANT: Make sure your multimeter test leads DO NOT interfere with the crankshaft pulley or the serpentine drive belt, since you'll be cranking the engine in one of the following steps. - 4
Reconnect the connector to the CKP sensor.
- 5
Turn the multimeter's dial to Volts AC.
- 6
Have your helper crank the engine when the test is set up and you're standing a safe distance from the engine.
- 7
Your multimeter should register an AC voltage between 0.5 to 1.2 Volts AC while the engine is cranking.
When the engine is not cranking, you should see 0 Volts AC.
NOTE: Your multimeter will not register a steady AC voltage. Instead, the reading will fluctuate between 0.5 to 1.2 Volts AC continually as the engine is cranking and only when the engine is cranking.
Let's interpret your test results:
CASE 1: The multimeter registered the indicated AC voltage with the engine cranking. This test result indicates that the CKP sensor is good.
Since the engine is not starting, take a look at the following tutorial for more testing suggestions:
CASE 2: The multimeter DID NOT register the indicated AC voltage with the engine cranking. This test result confirms that the CKP sensor is fried. Replace the crankshaft position sensor.
More 4.0L Ford Ranger (Mazda B4000) Tutorials
You can find a complete list of 4.0L Ford Ranger (Mazda B4000) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- Fuel Pressure Specifications (1991-2011 4.0L Ford Ranger And Mazda B4000).
- How To Test Engine Compression (1991-2011 4.0L Ford Ranger And Mazda B4000).
- How To Test For A Blown Head Gasket (1991-2011 4.0L Ford Ranger And Mazda B4000).
If this info saved the day, buy me a beer!
