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Crankshaft Position Sensor Testing
 
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Pelican Technical Article:

Crankshaft Position Sensor Testing

Nick Czerula

Time:

3 hours3 hrs

Tab:

$130

Talent:

*****

Tools:

10mm socket, flathead screwdriver, DVOM

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

Crankshaft position sensor

Hot Tip:

Work with a cool engine

Performance Gain:

Car will start and run well

Complementary Modification:

Replace air filter

The digital motor electronics (DME) engine management systems in Volvo V70 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 near the cylinder head, mounted in the transmission bell housing. The sensor reads a toothed reluctor wheel mounted to the end of the flywheel or torque converter. 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 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.

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.

The crankshaft position sensor (green arrow) is located near the cylinder head, mounted in the transmission bell housing near the radiator hose (red arrow).
Figure 1

The crankshaft position sensor (green arrow) is located near the cylinder head, mounted in the transmission bell housing near the radiator hose (red arrow).

Working at the intake air boot between the throttle housing and intake air housing, disconnect the electrical connector (red arrow) by pressing the release tab and pulling the connector straight off.
Figure 2

Working at the intake air boot between the throttle housing and intake air housing, disconnect the electrical connector (red arrow) by pressing the release tab and pulling the connector straight off.

Disconnect the breather hose (red arrow) by pulling it straight off the intake air duct.
Figure 3

Disconnect the breather hose (red arrow) by pulling it straight off the intake air duct.

Then, loosen the intake air duct clamps (green arrows).
Figure 4

Then, loosen the intake air duct clamps (green arrows).

Remove the intake air duct from the intake air housing and throttle housing.
Figure 5

Remove the intake air duct from the intake air housing and throttle housing. Then disconnect the breather hose (red arrow) located at the bottom of the duct (green arrow).

Working at the throttle housing, remove the four 10mm fasteners (green arrows).
Figure 6

Working at the throttle housing, remove the four 10mm fasteners (green arrows).

Pull the throttle housing off the intake manifold and lay it aside.
Figure 7

Pull the throttle housing off the intake manifold and lay it aside.

Working beneath the intake manifold, locate the crankshaft sensor electrical connector (green arrow).
Figure 8

Working beneath the intake manifold, locate the crankshaft sensor electrical connector (green arrow). The red arrow points to the intake manifold for orientation. You will do most of this part by feel, as it is difficult to see the sensors. Press the release tab (green arrow) while pulling the connector end (yellow arrow).

With the sensor disconnected, connect your DVOM to the two terminals (red arrows).
Figure 9

With the sensor disconnected, connect your DVOM to the two terminals (red arrows). Set your DVOM to A/C volts.

Reinstall the throttle housing.
Figure 10

Reinstall the throttle housing. Then remove the fuel pump fuse or relay. See our tech article on fuel pump testing for more information. With your DVOM connected, the positive lead to terminal 1 (red arrow) and the negative lead to terminal 2 (yellow arrow), crank the engine over. The volt meter should read about 50 millivolts. I normally see them around 30-50mv, depending on the battery and starter condition. You want to have a charged battery for good engine RPM when cranking.

You can also bench test the sensor when it is removed from the vehicle.
Figure 11

You can also bench test the sensor when it is removed from the vehicle. Use a long extension and a 10mm socket. Remove the crankshaft sensor fastener (green arrow).

Once the fastener is removed, check that the sensor is free by moving it side to side (red arrow).
Figure 12

Once the fastener is removed, check that the sensor is free by moving it side to side (red arrow). This also helps to free up a slightly frozen sensor.

Pull the crankshaft sensor out of the transmission bell housing.
Figure 13

Pull the crankshaft sensor out of the transmission bell housing. Feed the harness out of the engine with the sensor.

With the sensor removed, connect your DVOM to the two terminals.
Figure 14

With the sensor removed, connect your DVOM to the two terminals. Set your DVOM to A/C volts. Hold the sensor while moving a wrench across the tip. Monitor the DVOM. The voltage should fluctuate and create the same amount of voltage as during the engine cranking test. In this photo the wrench (green arrow) is close to the sensor (yellow arrow). The volt meter should read about 30 - 50 millivolts (red arrow). It is a bit tougher because you are breaking the magnetic field by hand and creating the voltage. You will have to move the wrench across the tip of the sensor quickly, back and forth to generate the A/C voltage.

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