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Camshaft Sensor Testing
 
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Pelican Technical Article:

Camshaft Sensor Testing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$0

Talent:

*****

Tools:

DVOM, backprobes, socket set, wrench

Applicable Models:

BMW Z3 (1996-02)

Performance Gain:

Remedy a check engine light

Complementary Modification:

If faulty; replace camshaft sensor, Change engine oil

The digital motor electronics (DME) engine management systems in BMW Z3 vehicles 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 the camshaft position sensors that help synchronize fuel injection and ignition. In addition, camshaft sensors serve as feedback devices for VANOS (variable camshaft timing) control (if equipped). 

When a camshaft sensor fails, the check engine light will illuminate and a fault code is stored. I have seen faulty sensors cause engine stalling and poor engine drivability. If you have a camshaft sensor fault code and your engine isn't running right, I suggest replacing the sensor first before other trouble shooting.

In this article, I'll go over the steps involved with testing the intake and exhaust camshaft position sensors.

To avoid marring the paint and trim, work with a plastic prying tool or wrap a screwdriver tip with masking tape before prying out body or interior items.

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 you're 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. 

w 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.

During the tests you will see what a working sensor will show. If your readings do not match, replace the sensor.

Models with 4-cylinder engine:

Using a scan tool, read fault codes to confirm a fault with your camshaft position sensor.

Four cylinder models utilize a single camshaft position sensor.
Figure 1

Four cylinder models utilize a single camshaft position sensor. (green arrow) It is located at the front of the cylinder head, in the timing cover. Remove the upper intake manifold. See our tech article on intake manifold removing.

To make getting to the sensor easier, I like to remove the secondary air pipe at the front of the cylinder head.
Figure 2

To make getting to the sensor easier, I like to remove the secondary air pipe at the front of the cylinder head. Squeeze the release tabs (green arrow), then pull the pipe straight off the secondary air valve to remove.

The camshaft sensor electrical connector is the forward mounted connector at the electrical junction, the electrical junction is in the center of the lower intake manifold, and accessible once upper intake manifold is removed (green arrow).
Figure 3

The camshaft sensor electrical connector is the forward mounted connector at the electrical junction, the electrical junction is in the center of the lower intake manifold, and accessible once upper intake manifold is removed (green arrow).

To access the camshaft sensor electrical connector for testing, you will have to remove the plastic cover on the wiring harness junction.
Figure 4

To access the camshaft sensor electrical connector for testing, you will have to remove the plastic cover on the wiring harness junction. Start by unclipping the four tabs on one side of the plastic cover (green arrows), then lift cover up, then unclip the four tabs on the opposite side of the cover. Once unclipped, remove the cover from the wiring harness junction.

With the cover removed, you now have access to the camshaft position sensor (green arrow) and crankshaft position sensor (yellow arrow) electrical connectors.
Figure 5

With the cover removed, you now have access to the camshaft position sensor (green arrow) and crankshaft position sensor (yellow arrow) electrical connectors.

Slide the camshaft electrical connector up and out of the plastic holder.
Figure 6

Slide the camshaft electrical connector up and out of the plastic holder. Testing with DVOM (sensor installed)

Terminal 1 is the sensor supply voltage.
Figure 7

Terminal 1 is the sensor supply voltage. (green arrow) Terminal 2 is sensor reference voltage / signal wire. (yellow arrow) Terminal 3 is the ground for the sensor provided by the DME. (purple arrow) Wiring color and terminal locations may vary. Check your model against a wiring diagram. Pin 1 Pin 2 Pin 3 Battery volts 5 volts (or 12, depending on year) Ground (0.1 volts) Turn the Key ON, but do not start the engine.

Connect you DVOM black lead to battery negative (yellow arrow), place DVOM on D/C volts.
Figure 8

Connect you DVOM black lead to battery negative (yellow arrow), place DVOM on D/C volts. The red lead will be used to probe electrical connector. Insert a backprobe into terminal 2 (green arrow), the middle terminal. Then connect the red lead of your DVOM to backprobe. (green arrow)

Rotate engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt.
Figure 9

Rotate engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt. Monitor DVOM for voltage to fluctuate from 12 volts to zero volts as the engine rotates. If voltage stays at 12 volts or 0 volts while you rotate engine, and does not fluctuate, the sensor is faulty. Sensor voltage should cycle twice per engine revolution, (0-12 volts, then 0-12 volts again, per full engine rotation). Testing with DVOM (sensor removed) You can also test sensor with it removed from engine. Turn the Key ON, but do not start the engine. Remove sensor from engine. See our tech article on camshaft sensor replacing. Connect you DVOM black lead to battery negative, place DVOM on D/C volts. The red lead will be used to probe electrical connector. Connect camshaft position sensor electrical connector, peel back 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 sensor while moving a wrench across tip. Monitor DVOM, voltage should fluctuate just as it should when rotating engine by hand.

In this photo the wrench (green arrow) is away from the sensor (yellow arrow), so the DVOM reads about 12 volts.
Figure 10

In this photo the wrench (green arrow) is away from the sensor (yellow arrow), so the DVOM reads about 12 volts.

Models with 6-cylinder engine:

Some of the photos in this tech article are from a similar BMW model with the same engine and DME system. The testing is the same as a Z3 model.
In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads about 0 volts.
Figure 11

In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads about 0 volts. 

Using a scan tool, read fault codes to determine which camshaft sensor you have to test.
Figure 12

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

On VANOS equipped models, you can check if your camshaft is currently functioned using your scan tool.
Figure 13

On VANOS equipped models, you can check if your camshaft is currently functioned using your scan tool. If you view live data of VANOS, there are readings for camshaft angle (green arrow). When a sensor is operating properly, this angle will change when engine RPM is raised and lowered. If this doesnÂÂÂÂÂ'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 DVOM (sensor installed)

Exhaust camshaft sensor is located at right front of cylinder head.
Figure 14

Exhaust camshaft sensor is located at right front of cylinder head. (green arrow)

Disconnect camshaft position sensor electrical connector by squeezing release tab and pulling off.
Figure 15

Disconnect camshaft position sensor electrical connector by squeezing release tab and pulling off.

With electrical connector disconnected, peel back electrical connector sealing boot or remove plastic cover (depending on equipment).
Figure 16

With electrical connector disconnected, peel back electrical connector sealing boot or remove plastic cover (depending on equipment). (green arrow)

Terminal 1 is the sensor supply voltage.
Figure 17

Terminal 1 is the sensor supply voltage. (green arrow) Terminal 2 is sensor reference voltage / signal wire. (yellow arrow) Terminal 3 is the ground for the sensor provided by the DME. (purple arrow) 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 you DVOM black lead to battery negative, place DVOM on D/C volts. The red lead will be used to probe electrical connector. Pin 1 Pin 2 Pin 3 Battery volts 5 volts (or 12, depending on year) Ground (0.1 volts) Connect camshaft position sensor electrical connector, peel back electrical connector sealing boot. (green arrow).

Insert a backprobe into terminal 2, the middle terminal.
Figure 18

Insert a backprobe into terminal 2, the middle terminal. Then connect the red lead of your DVOM to backprobe. (green arrow)

Rotate engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt.
Figure 19

Rotate engine clockwise by hand using a 22mm socket and ratchet on the crankshaft pulley bolt. Monitor 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 engine, and does not fluctuate, the sensor is faulty. Sensor voltage should cycle twice per engine revolution, ( 0-5 volts, then 0-5 volts again, per full engine rotation). Testing with DVOM (sensor removed) You can also test sensor with it removed from engine. Turn the Key ON, but do not start the engine. Remove sensor from engine. See our tech article on camshaft sensor replacing. Connect you DVOM black lead to battery negative, place DVOM on D/C volts. The red lead will be used to probe electrical connector. Connect camshaft position sensor electrical connector, peel back 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 sensor while moving a wrench across tip. Monitor DVOM, voltage should fluctuate just as it should when rotating engine by hand.

In this photo the wrench (green arrow) is away from the sensor (yellow arrow), so the DVOM reads 5 volts.
Figure 20

In this photo the wrench (green arrow) is away from the sensor (yellow arrow), so the DVOM reads 5 volts.

In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads 5 volts.
Figure 21

In this photo the wrench (green arrow) is close to the sensor (yellow arrow), so the DVOM reads 5 volts.

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Comments and Suggestions:
Carlos Comments: Good information; Thank you!
November 28, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
anton Comments: hi.
i have a z3 1996. m44. vin lb66020. have a code p0340.
im doing the test camshaft sensor .
my question is, pin#2 that voltaje must send 5v or 12v?
taks
July 13, 2016
  Followup from the Pelican Staff: I don't h ave the wiring for your vehicle. It could be either one, both would likely be OK readings if it were the reference voltage circuit. - Nick at Pelican Parts  

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Page last updated: Fri 12/9/2016 02:07:02 AM