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Crankshaft Position Sensor Testing
 
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Pelican Technical Article:

Crankshaft Position Sensor Testing

Nick Czerula

Time:

1 hours1 hrs

Tab:

$130

Talent:

*****

Tools:

T25 Torx, trim panel tool, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

R56 MINI Cooper Hatchback (2007-11)
R56 MINI Cooper S Hatchback (2007-11)

Parts Required:

Crankshaft position sensor, sealing O-ring

Hot Tip:

Work with a cool engine

Performance Gain:

Car will start and run well

Complementary Modification:

Replace camshaft sensors

The digital motor electronics (DME) engine management systems in MINI R56 vehicles uses the engine control module (ECM) to control fuel injection, ignition and other important drivetrain functions. The ECM sequentially triggers the fuel injectors to spray fuel into the intake ports and then, a split-second later, triggers the ignition coils to fire the spark plugs. This sequence of events is timed by using the crankshaft position. Using the signal from the crankshaft sensor, the ECM "knows" which cylinder is ready for fuel intake and then, later, for ignition.

The crankshaft position sensor is located below the starter motor, mounted in the engine block. The sensor reads a toothed reluctor wheel mounted to the end of the crankshaft. It then sends a signal to the DME used to identify cylinder location. If this signal is missing, for example from a faulty crankshaft sensor, then the engine will not start. You can consider the signal from the crankshaft sensor the RPM signal for the DME.

In this article, I'll go over the steps involved with testing the crankshaft position sensor. During the tests you will see what a working sensor will show. If your readings do not match, replace the sensor.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Jack up the front of your vehicle. See our tech article on jacking up your vehicle. Anytime you work under your MINI, make sure that you're wearing safety glasses or safety goggles.

The crankshaft position sensor (red arrow) is located below the starter motor, mounted in the engine block.
Figure 1

The crankshaft position sensor (red arrow) is located below the starter motor, mounted in the engine block. It's housed behind a plastic cover.

A quick way to see if your crankshaft sensor is preventing the engine from starting is to connect a MINI scan tool.
Figure 2

A quick way to see if your crankshaft sensor is preventing the engine from starting is to connect a MINI scan tool. Confirm it has current communication and idle status is active. Then check if actual RPM (green arrow) matches desired RPM (red arrow).

If cranking your engine and it will not start, check if engine idle is active.
Figure 3

If cranking your engine and it will not start, check if engine idle is active. Then check if actual RPM (green arrow) matches desired RPM (red arrow). If actual is zero, the sensor may be at fault. Some scan tools won't display live cranking voltage. This is when knowing your tool is key.

Working at the crankshaft sensor cover, using a trim panel tool, remove the center rivet (red arrows) from the cover.
Figure 4

Working at the crankshaft sensor cover, using a trim panel tool, remove the center rivet (red arrows) from the cover.

Remove the cover from the crankcase (red arrow).
Figure 5

Remove the cover from the crankcase (red arrow). This will expose the crankshaft sensor (green arrow).

Terminal 1 is the sensor supply voltage (yellow arrow).
Figure 6

Terminal 1 is the sensor supply voltage (yellow arrow). Terminal 2 is the ground for the sensor provided by the DME (green arrow). Terminal 3 is the sensor reference voltage / signal wire (red arrow). The wiring color and DME terminal locations may vary. Check your model against a wiring diagram. Turn the Key ON, but do not start the engine. Connect your DVOM black lead to battery negative. Place the DVOM on D/C volts. The red lead will be used to probe the electrical connector. Here's how the pins line up: Pin 1: 5 volts, Pin 2 Ground, around zero volts, Pin 3, sensor signal, zero or 12 volts.

With a backprobe connected to the sensor signal of pin 3, confirm that the digital signal is being produced by the sensor.
Figure 7

With a backprobe connected to the sensor signal of pin 3, confirm that the digital signal is being produced by the sensor. Working at the right side of the vehicle, loosen the two Phillips head splash shield fasteners (red arrows).

Rotate the splash shield (red arrow) and move it out of the way.
Figure 8

Rotate the splash shield (red arrow) and move it out of the way. This will give you room to work at the crankshaft pulley.

Install a 18mm socket and ratchet (green arrows) on the crankshaft pulley bolt.
Figure 9

Install a 18mm socket and ratchet (green arrows) on the crankshaft pulley bolt.

Now, check for the correct voltage on pins 1 and 2: Pin 1: 5 volts (red arrow), Pin 2 Ground, around zero volts (green arrow).
Figure 10

Now, check for the correct voltage on pins 1 and 2: Pin 1: 5 volts (red arrow), Pin 2 Ground, around zero volts (green arrow).

Connect the DVOM to the signal wire on pin 3.
Figure 11

Connect the DVOM to the signal wire on pin 3. Rotate the engine clockwise by hand using a 18mm socket and ratchet (yellow arrow) on the crankshaft pulley bolt. Monitor the DVOM for voltage to fluctuate from 12 (red arrow) volts to zero (green arrow) volts as the engine rotates. If voltage stays at 12 volts or 0 volts while you rotate the engine, and does not fluctuate, the sensor is faulty. The sensor reads the toothed wheel on the crankshaft (purple arrow). Each time it passes the sensor reads the voltage changes.

Testing with sensor removed: You can also test the sensor with it removed from the engine.
Figure 12

Testing with sensor removed: You can also test the sensor with it removed from the engine. Turn the Key ON, but do not start the engine. Remove the sensor from the engine. See our tech article on crankshaft sensor replacing. Connect your DVOM black lead to battery negative and place the DVOM on D/C volts. The red lead will be used to probe the electrical connector. Connect the camshaft position sensor electrical connector. Insert a backprobe into terminal 3. Then connect the red lead of your DVOM to the backprobe. Hold the sensor while moving a wrench across the tip. Monitor the DVOM. The voltage should fluctuate just as it should when rotating the engine by hand. In this photo the wrench (red arrow) is away from the sensor (yellow arrow), so the DVOM reads 0 volts.

Testing with sensor removed: In this photo the wrench (yellow arrow) is close to the sensor (red arrow), so the DVOM reads 12 volts.
Figure 13

Testing with sensor removed: In this photo the wrench (yellow arrow) is close to the sensor (red arrow), so the DVOM reads 12 volts. Voltage will be created as you come in contact with the sensor tip. It will not hold steady. It will rise to 12, then back to zero.






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