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OBJECTIVES
After studying Chapter 19, the reader will be able to:
1. Prepare for ASE Engine Performance (A8)
certification test content area “E” (Computerized
Engine Controls Diagnosis and Repair).
2. Discuss how crankshaft position sensors work.
3. List the methods that can be used to test CKP
sensors.
4. Describe the symptoms of a failed CMP sensor.
5. List how the operation of the CKP sensor affects
vehicle operation.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKSHAFT AND CAMSHAFT POSITION
SENSORS
• Purpose and Function
– The crankshaft position sensor is primarily responsible for
the following.
• Engine speed (RPM).
• Piston position for ignition timing control.
• Misfire detection.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKSHAFT AND CAMSHAFT POSITION
SENSORS
FIGURE 19-1 A typical magnetic crankshaft position sensor used on a General
Motors V-6 engine.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CRANKSHAFT AND CAMSHAFT POSITION
SENSORS
FIGURE 19-2 Some Halleffect sensors look like
magnetic sensors. This Halleffect camshaft reference
sensor and crankshaft
position sensor have an
electronic circuit built in that
creates a 0- to 5-volt signal as
shown at the bottom. These
Hall-effect sensors have three
wires: a power supply (8 volts)
from the computer (controller);
a signal (0 to 5 volts); and a
signal ground.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
Parts and Operation
• Some characteristics of a magnetic sensor include:
– Two-wire sensors.
– Sensors mounted near a gear or notched wheel.
– Sensors where the faster the toothed wheel moves
past the sensor, the higher the frequency of the
output signal.
– Magnetic position sensors generate a higher voltage
signal with increased engine speed.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
Parts and Operation
FIGURE 19-3 A magnetic
sensor uses a permanent
magnet surrounded by a coil of
wire. The notches of the
crankshaft (or camshaft) create
a variable magnetic field
strength around the coil. When
a metallic section is close to
the sensor, the magnetic field
is stronger because metal is a
better conductor of magnetic
lines of force than air.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
• Testing Magnetic Position Sensors
–
–
–
–
Check the sensor connection and wiring.
Check that the sensor itself is magnetic.
Check the resistance of a magnetic sensor.
Scope testing a magnetic sensor.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
FIGURE 19-4 A magnetic sensor being tested for magnetism. This sensor was
able to hold a bolt and had about the same magnetic strength as a new sensor.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
FIGURE 19-5 An AC voltage is produced by a magnetic sensor. Most sensors
should produce at least 0.1 volt AC while the engine is cranking if the pickup wheel
has many teeth. If the pickup wheel has only a few teeth, you may need to switch
the meter to read DC volts and watch the display for a jump in voltage as the teeth
pass the magnetic sensor. (Courtesy of Fluke Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
FIGURE 19-6 A magnetic sensor
connected to a digital storage
oscilloscope.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC POSITION SENSOR
FIGURE 19-7 (a) Magnetic sensor waveform as shown on a digital storage
oscilloscope. (b) A sync notch provides a signal to the computer that cylinder
number one is at top dead center (TDC). (Courtesy of Fluke Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HALL-EFFECT DIGITAL SENSORS
• Parts and Operation
– The typical Hall-effect sensor has three wires:
• Power (can be 8 to 12 volts)
• Ground
• Signal
• Testing Hall-Effect Sensors
– If the scope pattern indicates a problem or a scope is not
available, other tests include:
• Check the sensor connection and wiring.
• Check the sensor damage.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HALL-EFFECT DIGITAL SENSORS
FIGURE 19-8 (a) The connection required to test a Hall-effect sensor. (b) A typical
waveform from a Hall-effect sensor. (Courtesy of Fluke Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HALL-EFFECT DIGITAL SENSORS
FIGURE 19-9 The waveform from a Hall-effect sensor (switch) should be checked
for consistency and sharp transitions. (Courtesy of Fluke Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC-RESISTIVE SENSORS
• Parts and Operation
– A magnetic-resistive sensor (abbreviated MRE) is similar
to a magnetic sensor but, instead of producing an analog
voltage signal, the electronics inside the sensor itself
generate a digital on/off signal or an output.
• Testing a Magnetic-Resistive Sensor
– If the scope pattern indicates a problem or a scope is not
available, other tests include:
• Check the sensor connection and wiring.
• Check that the sensor itself is magnetic.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
MAGNETIC-RESISTIVE SENSORS
FIGURE 19-10 The input signals to a magnetic resistive sensor and the electronic
circuits inside the sensor convert them to a digital (on and off) signal.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
OPTICAL SENSORS
• Parts and Operation
– Optical sensors typically use a photo diode and/or a photo
transistor and a slotted disk to detect distributor position.
– The output is a digital on/off (square wave) signal that is
very accurate.
• Testing Optical Sensors
– If the scope pattern indicates a problem or a scope is not
available, other tests include:
• Check the sensor connection and wiring.
• Check the sensor or wiring for damage.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
OPTICAL SENSORS
FIGURE 19-11 (a) The lowresolution signal has the same
number of pulses as the
engine has cylinders. (b) A
dual trace pattern showing
both the low-resolution signal
and the high-resolution signals
that usually represent 1 degree
of rotation. (Courtesy of Fluke
Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PCM USES OF THE CRANKSHAFT AND
CAMSHAFT POSITION SENSOR
• The crankshaft and camshaft position sensors are used by
the powertrain control module for many functions including
the following.
– The crankshaft position is normally used to determine engine speed
(RPM).
– Camshaft position sensor information is usually used to determine the
cylinder position for fuel control (when to trigger the injectors).
– Engine speed input is used to calculate IAC counts to maintain the
target idle speed.
– Crankshaft position sensors are used primarily as the spark timing
input sensor.
– The crankshaft position sensor is used as an input for traction control.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PCM USES OF THE CRANKSHAFT AND
CAMSHAFT POSITION SENSOR
FIGURE 19-12 A General
Motors camshaft sensor (CMP)
pattern as shown on a digital
storage oscilloscope. The
camshaft sensor is used by the
computer to help determine the
engine crankshaft speed (OBD
II) and camshaft position.
Besides ignition timing and
misfire input information, the
camshaft sensor signal is also
used for fuel-injection pulses.
This signal uses different pulse
widths to signal the computer
the exact position of the
distributor. (Courtesy of Fluke
Corporation)
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PCM USES OF THE CRANKSHAFT AND
CAMSHAFT POSITION SENSOR
• Re-Synchronizing the Crankshaft Position
Sensor
– Whenever the PCM or the crankshaft position sensor are
replaced, the new part must be “learned” or synchronized
before the engine will operate correctly.
– Most scan tools are capable of performing the re-learn
process, which often calls for accelerating the engine for
the new parameters to be learned.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
PCM USES OF THE CRANKSHAFT AND
CAMSHAFT POSITION SENSOR
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1. The crankshaft position (CKP) sensor is used as an input
sensor to the PCM for engine speed (RPM) and piston
position for spark timing control.
2. A camshaft position sensor is also called a cylinder
identification (CID) sensor and is primarily used to time the
sequential fuel injection.
3. A magnetic position sensor generates an analog voltage
signal.
4. A Hall-effect position sensor generates a digital (on and off)
voltage signal.
5. A magnetic-resistive position sensor creates a digital output
signal.
6. An optical position sensor creates a digital output signal.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
REVIEW QUESTIONS
1. What is the primary purpose for a crankshaft position
(CKP) sensor?
2. What is the primary purpose for a camshaft position (CMP)
sensor?
3. How does a magnetic sensor work, and how is it tested?
4. How does a Hall-effect sensor work, and how is it tested?
5. How does a magnetic-resistive sensor work, and how is it
tested?
6. How does an optical sensor work, and how is it tested?
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. A magnetic position sensor is being tested with an
ohmmeter. The display reads 102 KΩ. Technician
A says that the sensor resistance is within the
normal range. Technician B says that the coil
winding inside the sensor is shorted. Which
technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. A magnetic position sensor is being tested with an
ohmmeter. The display reads 102 KΩ. Technician
A says that the sensor resistance is within the
normal range. Technician B says that the coil
winding inside the sensor is shorted. Which
technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. Technician A says that the crankshaft position
(CKP) sensor is used by the PCM to determine
engine speed (RPM). Technician B says that the
camshaft position (CMP) is used by the PCM to
determine the timing of the fuel injectors. Which
technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. Technician A says that the crankshaft position
(CKP) sensor is used by the PCM to determine
engine speed (RPM). Technician B says that the
camshaft position (CMP) is used by the PCM to
determine the timing of the fuel injectors. Which
technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. Which sensor produces an analog (varying
voltage) output signal?
a)
b)
c)
d)
Magnetic
Hall-effect
Optical
Magnetic-resistive
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. Which sensor produces an analog (varying
voltage) output signal?
a)
b)
c)
d)
Magnetic
Hall-effect
Optical
Magnetic-resistive
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. Which type of sensor is most likely to be used to
sense each degree of rotation of the crankshaft?
a)
b)
c)
d)
Magnetic
Hall-effect
Optical
Magnetic-resistive
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. Which type of sensor is most likely to be used to
sense each degree of rotation of the crankshaft?
a)
b)
c)
d)
Magnetic
Hall-effect
Optical
Magnetic-resistive
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. A magnetic sensor usually has how many wires?
a)
b)
c)
d)
1
2
3
4
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. A magnetic sensor usually has how many wires?
a)
b)
c)
d)
1
2
3
4
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. A Hall-effect sensor usually has how many wires?
a)
b)
c)
d)
1
2
3
4
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. A Hall-effect sensor usually has how many wires?
a)
b)
c)
d)
1
2
3
4
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. In Figure 19-13, the top
waveform is produced by
what type of sensor?
a)
b)
c)
d)
Magnetic
Hall-effect
Either a or b
Neither a nor b
FIGURE 19-13 Typical crankshaft position sensor waveforms.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. In Figure 19-13, the top
waveform is produced by
what type of sensor?
a)
b)
c)
d)
Magnetic
Hall-effect
Either a or b
Neither a nor b
FIGURE 19-13 Typical crankshaft position sensor waveforms.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. In Figure 19-13, the
bottom waveform is
produced by what type of
sensor?
a)
b)
c)
d)
Magnetic
Hall-effect
Either a or b
Neither a nor b
FIGURE 19-13 Typical crankshaft position sensor waveforms.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. In Figure 19-13, the
bottom waveform is
produced by what type of
sensor?
a)
b)
c)
d)
Magnetic
Hall-effect
Either a or b
Neither a nor b
FIGURE 19-13 Typical crankshaft position sensor waveforms.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. Extending engine cranking before starting is a
symptom of a defective _____ sensor.
a)
b)
c)
d)
Crankshaft position (CKP)
Camshaft position (CMP)
Both CKP and CMP
Neither CKP nor CMP
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. Extending engine cranking before starting is a
symptom of a defective _____ sensor.
a)
b)
c)
d)
Crankshaft position (CKP)
Camshaft position (CMP)
Both CKP and CMP
Neither CKP nor CMP
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. A P0337 DTC is being discussed. Technician A
says that a broken CKP reluctor wheel could be
the cause. Technician B says that a defective CKP
could be the cause. Which technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. A P0337 DTC is being discussed. Technician A
says that a broken CKP reluctor wheel could be
the cause. Technician B says that a defective CKP
could be the cause. Which technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458