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M54 Engine Camshaft Position Sensor Testing
 
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Pelican Technical Article:

M54 Engine Camshaft Position Sensor Testing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$50

Talent:

*****

Tools:

DVOM, backprobes, socket set

Applicable Models:

BMW X3 Sport Utility (2004-06)

Parts Required:

Camshaft sensor, sealing O-ring

Hot Tip:

Always note and double-check your test results

Performance Gain:

Remedy fault codes

The digital motor electronics (DME) engine management systems in BMW E83 vehicles with an M54 engine use 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 crankshaft position information. Using the signal from the crankshaft sensor, the ECM "knows" which cylinder is ready for fuel intake and then, later, for ignition. 

However, in addition to the crankshaft position signal, the ECM needs a signal to distinguish the crankshaft valve-overlap top-dead-center (TDC) position from the TDC just prior to the power stroke. This signal is provided by camshaft position sensors which help synchronize fuel injection and ignition. In addition, camshaft sensors serve as feedback devices for VANOS (variable camshaft timing) control.

In this tech article we will go about testing BMW X3 camshaft position sensors on models with an M54 engine. Other engines are similar, and the same test techniques can be applied. The exhaust camshaft sensor will be shown in the photos. Testing the intake camshaft sensor is similar. A faulty camshaft sensor will set a fault code and possibly create engine drivability problems such as rough idle, engine stalling and misfire.

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. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Using a BMW scan tool, read the fault codes to determine which camshaft position sensor you have to test.
Figure 1

Using a BMW scan tool, read the fault codes to determine which camshaft position sensor you have to test. Shown here, the intake camshaft position sensor is setting a fault code.

You can check if your camshaft position sensor is currently functioning using your BMW scan tool.
Figure 2

You can check if your camshaft position sensor is currently functioning using your BMW scan tool. If you view live data of VANOS, there is a reading for the camshaft angle (green arrow). When a sensor is operating properly, this angle will change when engine RPM is raised and lowered. If this doesn't change, it indicates a fault. This test is best performed when you have a camshaft sensor code, as other DME system faults can cause camshaft angle not to change

Testing with exhaust sensor installed: The exhaust camshaft sensor is located at the right front of the cylinder head (red arrow).
Figure 3

Testing with exhaust sensor installed: The exhaust camshaft sensor is located at the right front of the cylinder head (red arrow).

Testing with exhaust sensor installed: Disconnect the camshaft position sensor electrical connector by squeezing the release tabs and pulling it straight off.
Figure 4

Testing with exhaust sensor installed: Disconnect the camshaft position sensor electrical connector by squeezing the release tabs and pulling it straight off.

Testing with exhaust sensor installed: With the electrical connector disconnected, unclip and remove the harness protector.
Figure 5

Testing with exhaust sensor installed: With the electrical connector disconnected, unclip and remove the harness protector.

Testing with exhaust sensor installed: Terminal 1 is the sensor supply voltage (yellow arrow).
Figure 6

Testing with exhaust sensor installed: Terminal 1 is the sensor supply voltage (yellow arrow). Terminal 2 is the sensor reference voltage / signal wire (red arrow). Terminal 3 is the ground for the sensor provided by the DME (blue 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. Pin 1: battery volts. Pin 2 5 or 12 volts (depending on model year), Pin 3 Ground, around zero volts.

Testing with exhaust sensor installed: Connect the camshaft position sensor electrical connector.
Figure 7

Testing with exhaust sensor installed: Connect the camshaft position sensor electrical connector. Peel back the electrical connector sealing boot. Insert a backprobe into terminal 2, the middle terminal. Then connect the red lead of your DVOM to backprobe (yellow arrow).

Testing with exhaust sensor installed: Rotate the engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt (red arrow).
Figure 8

Testing with exhaust sensor installed: Rotate the engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt (red arrow). Monitor the DVOM for voltage to fluctuate from 5 volts to zero volts as the engine rotates. If voltage stays at 5 volts or 0 volts while you rotate the engine, and does not fluctuate, the sensor is faulty. The sensor voltage should cycle twice per engine revolution, (0 - 5 volts, then 0 - 5 volts again, per full engine rotation).

Testing with intake sensor installed: The intake camshaft sensor is located at the left front of the cylinder head.
Figure 9

Testing with intake sensor installed: The intake camshaft sensor is located at the left front of the cylinder head. However, testing will take place at the electrical junction box near the alternator. The camshaft sensor electrical connector (yellow arrow) is located at the electrical junction behind the alternator (red arrow). The connector can be accessed without removing the air filter housing. If you are having trouble, see our tech article on intake air ducts and housing replacing.

Testing with intake sensor installed: Disconnect the camshaft sensor electrical connector by pressing the release wire (red arrow) and pulling the male (yellow arrow) end of the connector out of the electrical junction.
Figure 10

Testing with intake sensor installed: Disconnect the camshaft sensor electrical connector by pressing the release wire (red arrow) and pulling the male (yellow arrow) end of the connector out of the electrical junction.

Testing with intake sensor installed: With the electrical connector disconnected, peel back the harness protector.
Figure 11

Testing with intake sensor installed: With the electrical connector disconnected, peel back the harness protector. Terminal 1 is the sensor supply voltage (yellow arrow). Terminal 2 is the sensor reference voltage / signal wire (green arrow). Terminal 3 is the ground for the sensor provided by the DME (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. Pin 1: battery volts. Pin 2 5 or 12 volts (depending on model year), Pin 3 Ground, around zero volts.

Testing with intake sensor installed: Rotate the engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt (red arrow).
Figure 12

Testing with intake sensor installed: Rotate the engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt (red arrow). Monitor the DVOM for voltage to fluctuate from 5 volts to zero volts as the engine rotates. If voltage stays at 5 volts or 0 volts while you rotate the engine, and does not fluctuate, the sensor is faulty. The sensor voltage should cycle twice per engine revolution, (0 - 5 volts, then 0 - 5 volts again, per full engine rotation).

Testing with sensor removed: You can also test the sensor with it removed from the engine.
Figure 13

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 camshaft 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. Peel back the electrical connector sealing boot (green arrow). Insert a backprobe into terminal 2, the middle terminal. Then connect the red lead of your DVOM to 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 (green arrow) is away from the sensor (yellow arrow), so the DVOM reads 5 volts.

Testing with a sensor removed: In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads 0 volts.
Figure 14

Testing with a sensor removed: In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads 0 volts.

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Page last updated: Fri 7/21/2017 03:34:25 AM