Transcript
Learning Guide BODY ELECTRICAL SPECIALIST ELECTRICAL DIAGNOSIS AND REPAIR – WAVEFORM ANALYSIS
COURSE NUMBER: BE002-03
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Notice Due to the wide range of vehicles makes and models, the information given during the class will be general in nature and should not be taken as specific to any vehicle/unit. Please consult manufacturer specifications for the correct number/specifications and repair procedures for the vehicle you are testing. This document is meant to be used as a guideline only.
For further information, please contact toll-free:
1-855-813-2101 or email
[email protected]
No part of this book may be reproduced, stored in any retrieval system or transmitted in any form or by any means (including but not limited to electronic, mechanical, photocopying and recording) without prior written permission of CARS Training Network Inc. This applies to all text, illustrations, tables and charts. Copyright © 2014 CARS Training Network Inc
Page ii
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Table of Contents Table of Contents ................................................................................................................................... iii Introduction ............................................................................................................................................. 1 Objectives ............................................................................................................................................................................. 1
Oscilloscope Operation Overview.......................................................................................................... 2 Oscilloscope Display ............................................................................................................................................................ 2 Voltage Adjustments ............................................................................................................................................................................ 3 Time Adjustments ................................................................................................................................................................................ 3 Trigger Point ........................................................................................................................................................................................ 4 Slope Adjustment ................................................................................................................................................................................. 4
Waveform Patterns ................................................................................................................................................................ 5 Square Wave ........................................................................................................................................................................................ 5 Rectangular Wave ................................................................................................................................................................................ 5 Sine Wave ............................................................................................................................................................................................ 5
Waveform Pattern Terms ...................................................................................................................................................... 6 Amplitude ............................................................................................................................................................................................ 6 Peak to Peak Amplitude ....................................................................................................................................................................... 6 Period ................................................................................................................................................................................................... 7 Frequency ............................................................................................................................................................................................ 7 Duty Cycle ........................................................................................................................................................................................... 8
Modis Lab Scope ..................................................................................................................................... 9 Modis Lab Scope Plug-In ..................................................................................................................................................... 9 Test Leads ........................................................................................................................................................................... 10 Channel 1 Test Lead .......................................................................................................................................................................... 10 Channel 2 Test Lead .......................................................................................................................................................................... 11 Channel 3 and 4 Test Leads ............................................................................................................................................................... 11
Modis Main Screen ............................................................................................................................................................. 12 Lab Scope Controls ............................................................................................................................................................................ 12 Lab Scope Display ............................................................................................................................................................................. 13 Test Probe Selection .......................................................................................................................................................................... 14
Page iii
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis Voltage Adjustment ........................................................................................................................................................................... 14 Signal Zero Offset .............................................................................................................................................................................. 15 Time Adjustments .............................................................................................................................................................................. 16
Modis Lab Scope Functions ................................................................................................................. 17 Trigger Point ....................................................................................................................................................................... 17 Trigger Point Adjustments ................................................................................................................................................................. 18 Trigger Slope ..................................................................................................................................................................................... 18
Cursors ................................................................................................................................................................................ 19
Genisys Scope Module .......................................................................................................................... 20 Scope Module ..................................................................................................................................................................... 21 Test Probes .......................................................................................................................................................................... 21 Genisys Main Screen .......................................................................................................................................................... 22 Lab Scope Panel Setup ........................................................................................................................................................ 23 Volts Per Division .............................................................................................................................................................................. 23 Zero Point Adjustment ....................................................................................................................................................................... 24 Time Per Division .............................................................................................................................................................................. 24
Genisys Scope Module Functions ........................................................................................................ 25 Auto Setup .......................................................................................................................................................................... 25 Trigger Point ...................................................................................................................................................................................... 25
Cursors ................................................................................................................................................................................ 27 Horizontal Cursors ............................................................................................................................................................................. 27 Vertical Cursors ................................................................................................................................................................................. 28
Sample Waveforms ............................................................................................................................................................. 29 Magnetic Wheel Speed Sensor........................................................................................................................................................... 29 Hall Effect Crankshaft Position Sensor .............................................................................................................................................. 30 Engine Coolant Temperature Sensor.................................................................................................................................................. 31 Mass Airflow Sensor.......................................................................................................................................................................... 32
Page iv
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Introduction OBJECTIVES Upon successful completion of this segment, the participant will be able to:
Understand the usage of an automotive oscilloscope’s settings
Understand the importance of correct testing procedures
Identify a number of common automotive signals
Recognize normal and abnormal waveforms
Page 1
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Oscilloscope Operation Overview An oscilloscope is an electrical measurement instrument used to display and analyze a waveform of electrical signals. An oscilloscope draws a graph of voltage signals over a period of time and displays it on a screen. Depending on the model, a typical oscilloscope can display alternating current (AC) and direct current (DC) pulse waveforms in a frequency of approximately 1 hertz (Hz) to greater than several hundred megahertz (MHz).
OSCILLOSCOPE DISPLAY Generally, the oscilloscope display is broken up into ten horizontal divisions and eight vertical divisions. Time is displayed from left to right on the horizontal divisions. Voltage or current signal values are displayed on the vertical divisions with positive values going upward and negative values going downward.
One Division Voltage or Current Signal
TIME
Page 2
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Voltage Adjustments On the live oscilloscope, which we are using, adjustments for voltage per division are made by turning the dial to the desired voltage.
5 Volts Per Division This image shows a waveform pattern adjusted to 5 volts per division.
1 Volt Per Division By decreasing the voltage to 1 volt per division, as shown in the lower image, we stretch the waveform pattern vertically which provides a better view of the pattern for analysis.
Time Adjustments
10 Milliseconds Per Division
To further adjust the previous waveform for analysis, we can change the time from 10 milliseconds per division to 2 milliseconds per division.
2 Milliseconds Per Division By decreasing the time per division we have spread the waveform pattern out horizontally providing a better view for analyzing each individual square wave in the pattern.
Page 3
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
On multi-channel oscilloscopes, voltage per division can be adjusted individually for each channel input. When adjusting time per division on multi-channel oscilloscopes, the adjustments will be the same on all the channel inputs, which is to say, time per division cannot be adjusted individually for each channel. 1 Volt Per Division
Trigger Point The trigger point is the voltage level at which the oscilloscope starts to display the waveform pattern on the left of the screen. On an Alternating Current (AC) signal input, the trigger point can be adjusted to either a positive or negative voltage level. Adjusting the trigger point can assist with stabilizing the waveform pattern for better viewing.
Trigger Point at 0 Volts
Trigger Point at 2 Volts
Rising Slope
Slope Adjustment The waveform can be set from the trigger point to start for either an increasing or decreasing voltage level. This is called the “Slope” adjustment. If a rising slope is selected, the waveform pattern will start at the selected trigger point and will show voltage signal input as it increases from the trigger point.
Trigger Point
Falling Slope
If a falling slope is selected the waveform pattern will show voltage signal input as it decreases from the selected trigger point.
Page 4
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
WAVEFORM PATTERNS Square Wave A true square wave has straight vertical and horizontal lines with sharp square edged corners and has equal periods of time spent between high and low states.
0 Volts
This waveform may also be seen on the control circuits of actuators and solenoids with a 50% duty cycle.
Equal time between high and low states
Rectangular Wave Probably the most common waveform you will see is the rectangular wave. This is similar to a true square wave and, in cases, is also referred to as a square wave. However, the wave does not spend equal time between high and low states. This type of waveform can also be seen on digital electronics, communication lines and on some Mass Airflow Sensors (MAFS).
0 Volts
Difference in time between high and low states
Sine Wave Sine waves are commonly seen on components that produce alternating currents such as alternators and magnetic wheel speed sensors. Some vehicle manufactures still utilize magnetic crankshaft and camshaft position sensors. These also produce a sine wave.
+ _ _
0 Volts
Page 5
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
WAVEFORM PATTERN TERMS Amplitude Amplitude is the amount of vertical movement of the waveform from the zero reference line and is measured in volts or amps depending on the type of signal that is being received.
Amplitude
On sine waveform patterns, the movement above or below the zero reference line is termed as “Peak Amplitude”.
Peak Amplitudes
Peak to Peak Amplitude The term Peak to Peak Amplitude is commonly related to sine waveform patterns. This is the value of total vertical displacement between the peak of the positive wave to the peak of the negative wave. This is commonly measured as a voltage value.
Peak to Peak Amplitude
Page 6
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Period
Period is the time required for a repetitive signal to complete one cycle. As an example, the time for a sine wave that starts at the zero reference goes through both the positive and negative oscillations and back to the zero reference, is a period.
0 Ref
Period or One Cycle
0 Ref
Frequency Frequency is the number of times a signal completes a full cycle or period within one second. This is measured in hertz (Hz).
One Second
= 3Hz
0 Ref
One Cycle
One Second
= 2Hz 0 Ref
One Cycle
Page 7
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Duty Cycle Duty cycle is the percentage of the ON time to the OFF time of a rectangular waveform in one cycle or period. As an example, a rectangular waveform pattern that requires two seconds to complete a cycle or period and has an ON time of 0.5 seconds and an OFF time of 1.5 seconds, will have a 25% duty cycle.
0.5 Seconds
= 25% Duty Cycle
Period 2 Seconds
Page 8
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Modis Lab Scope The Modis Lab Scope is a four channel oscilloscope and is designed for automotive diagnostics. It is capable of displaying waveform patterns for a variety of sensors, actuators and control circuits on a vehicle.
MODIS LAB SCOPE PLUG-IN The lab scope provides the following ports for connecting the test leads that are color coded for easy hook-up. The black ground port is the common ground for the shielded test leads that require an additional ground. The channel ports are color coded as follows:
Channel 1 – yellow
Channel 2 – green
Channel 3 – blue
Channel 4 – red
The port colors correspond to the trace colors that are displayed on the oscilloscope screen for each channel. Channel 3 and 4 ports are also used for the negative and positive leads respectively when utilizing the Digital Volt Ohm Meter (DVOM) function of the Modis.
Page 9
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
TEST LEADS The test leads are color coded to the appropriate channel ports.
Channel 1 Test Lead The yellow channel 1 test lead is a shielded cable which has a separate ground lead for signals that require additional grounding.
The test lead ends that are being connected to the lab scope include the yellow channel 1 input, a black common ground which is plugged into the common ground port and a black stackable common ground end that can be used when another test lead requires a connection to common ground.
When another lead requires a connection to common ground, it is connected to the loose stackable common ground end.
Page 10
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Channel 2 Test Lead
As with the channel 1 test lead the green channel 2 test lead is a shielded cable.
A shielded cable helps prevent electromagnetic induction from affecting the signal inputs to the lab scope. The channel 2 test lead has a green end that is connected to the green channel port of the lab scope. The black stackable ground end is connected to the loose black stackable end of the channel 1 test lead for grounding the cable’s shielding.
Channel 3 and 4 Test Leads Channel 3 and 4 test leads are just simple one wire test leads. They are not shielded nor do they have a common ground wire. When using the DVOM function of the Modis, the channel 3 test lead will be used as the negative lead and the channel 4 test lead is used as the positive lead.
Page 11
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
MODIS MAIN SCREEN To access the lab scope on the Modis select “Scope”, “Lab Scope” then “4 Ch Lab Scope”.
Lab Scope Controls 1) Selects the channel to be adjusted 2) Selects the type of probes or leads being used 3) Selects the electronic measurement range 4) Adjusts the base line or zero point for the selected channel 5) Adjusts the time it takes the scope pattern to sweep across the screen. Adjustments made here affect all channels. 6) Selects the channel in which the trigger is to be adjusted. 7) Adjust the trigger point to either rising or falling.
1
2
3
4
5
6
7
8
8) Changes the position of the set trigger point on the display screen. Selections and adjustments of the controls are made using the Modis Thumb Pad and the Yes (Y) and No (N) buttons.
Page 12
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Lab Scope Display When selected, the “Ch 1” in the channel control bar allows you to turn ON and OFF displaying channels 1 to 4.
When a channel is turned ON, the channel number with the associated color of the channel port will be displayed on the right side of the screen. The waveform trace line color of the channels also corresponds with the color of the channel port for easy identification. The position of the channel number on the right side of the screen represents the base line or zero point for the channel.
Whatever channel that is displayed in the left Channel Bar, the voltage at each division is displayed on the left side of the screen.
Page 13
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Test Probe Selection By selecting the “Test Lead” button on the channel control bar as shown in this picture, brings up a list of various optional probes that can be connected to the Modis lab scope.
Voltage Adjustment Adjustments for voltage per division are made by selecting the voltage scale on the Channel Control Bar.
Page 14
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Signal Zero Offset The “Signal Zero Offset” moves the selected channel’s zero point or base line up or down within the display screen area. Where the channel number and color are displayed to the right of the scope screen represents the zero point or base line of that waveform pattern. To change the position, the desired channel must be selected then select the Signal Zero Offset control. The zero point can now be moved up and down on the scope screen with the Thumb Pad of the scan tool to position the waveform pattern within the screen as desired.
Zero Point or Base Line for Channel 3
Page 15
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Time Adjustments Selecting “Sweep” on the lower tool bar of the lab scope allows adjustment for the time display of the waveform pattern. When selecting a time unit from the pop-up list it refers to the time it takes the waveform pattern to sweep across the all ten horizontal divisions of the scope screen and is not the time per division.
Time per division is shown at the bottom of the scope screen which is one tenth of the time sweep that has been selected.
Page 16
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Modis Lab Scope Functions TRIGGER POINT The trigger point is the point at which the waveform pattern starts on the scope screen. Setting the trigger point stabilizes the waveform pattern and prevents it from walking or oscillating across the scope screen—making it difficult to analyze. The trigger point can be adjusted individually for each channel that is turned ON to any point vertically and horizontally on the scope screen. By selecting “Ch 1, 2, 3, or 4” in the “Display Trigger” tool bar allows selection of the desired channel for which the trigger point is to be adjusted or to view the settings of the trigger point position. The channels that are not active will be ghosted in the pull up list.
Channels 2 and 4 Ghosted (not activated)
Page 17
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Trigger Point Adjustments By selecting the desired channel in which the trigger point is to be adjusted, a small cross hair appears on the screen in the color that corresponds with the channel port selection and color. Selecting the Trigger Point Adjustment button brings up the trigger point position information. The trigger point voltage must be within the voltage range of the input signal for the trigger to take place.
Trigger Point Indicator
Once triggered, the waveform pattern will be locked to that position preventing the waveform from walking across the screen. Using the Modis thumb pad, the position of the trigger point can be moved vertically and horizontally anywhere on the scope screen.
Trigger Point Position
Trigger Point Adjustments
Trigger Slope By selecting the Trigger Slope button, we can change the waveform to show the input signal either increasing or decreasing from the set trigger point. This allows for positioning, viewing and analyzing desired portions of the waveform pattern on the scope screen.
Trigger Point
Signal Voltage Increasing From Trigger Point
Signal Voltage Decreasing From Trigger Point
Trigger Slope Page 18
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
CURSORS The Cursor control button is located on the top tool bar and is activated by highlighting the button and pressing “Y” on the Modis thumb controls. Pressing “Y” again allows you to select between cursor 1 and 2. Once the desired cursor is selected, using left or right on the thumb pad moves the highlighted cursor left or right across the screen. To check the signal voltages of the waveform at the positions of the cursors, select “Pause” in the top tool bar to freeze the waveform. A display box then appears in the top right of the scope screen. The voltage values at the positions of cursors 1 and 2 on the waveform are displayed along with the frequency and time of the signals between the cursors.
Cursor Control Button
Pause Play Button
Cursor Position Values
Highlighte d Cursor
Page 19
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Genisys Scope Module The Genisys Scope Module is a four channel oscilloscope that is designed for automotive diagnostics.
This tool is capable of displaying waveform patterns for a variety of sensors, actuators and control circuits on a vehicle.
The Genisys can show up to four waveform patterns on one screen.
The scope module has the ability to view the following signals:
Ohms (channel 1 only)
Amps
DC Volts
AC volts
Each channel can be manually setup for the following:
Time division
Voltage division
Horizontal or vertical cursors
Trigger point
Grid ON/OFF
Page 20
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
SCOPE MODULE The optional Scope Module connects to the Hardware Interface Port (HIP) on the back of the Genisys scan tool. The scope module provides ports for connecting the test leads which are color coded for easy hook-up. The black ground port is the common ground for all channels. The port colors correspond to the trace colors that are displayed on the oscilloscope screen for each channel.
TEST PROBES The test probes are shielded leads which are color coded to the appropriate channel ports. Also available as an option are the current, KV and synchronizing probes.
Sync Probe
KV Probe
Page 21
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
GENISYS MAIN SCREEN To access the scope module from the Genisys main screen, perform the following: Select and enter: 1. Diagnostic Tool Box 2. Scope with InfoTech 3. Scope 4. Lab Scope
1)
2)
3)
4)
Page 22
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
LAB SCOPE PANEL SETUP When the Lab Scope Panel Setup appears, this allows you to turn ON and assign a colored channel port to the channels, set the type of measurement values and range of the measurements.
The directional up and down keys are used to highlight the selection that is to be changed (Channel, Measure, Range) and the left and right keys are used to the values for that selection.
Once the appropriate channels have been turned ON, selecting “Auto Setup” with the corresponding function key will automatically setup the waveforms based on the inputs to the scope module.
Volts Per Division Adjustments for voltage per division are made by highlighting the voltage value under “Volts/div”. The volts per division are changed by pressing left and right on the directional key.
Page 23
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Zero Point Adjustment The zero point or base line adjustments are made by pressing down once on the directional key when the “Volts/div” is highlighted. This removes the highlight from the channel identification box that is located on the zero point of the selected channel.
At this point pressing left and right on the directional key moves the zero point up and down on the screen to the technician’s preference.
Zero Point (Channel Identification Box Not Highlighted)
Time Per Division Adjustments for time per division are made by highlighting the time value under “Time/div”. The time per division is changed by pressing left and right on the directional key.
20 ms Per Division
1 ms Per Division
Page 24
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Genisys Scope Module Functions AUTO SETUP When the appropriate channels have been turned ON at the “Lab Scope Panel Setup”, selecting “Auto Setup” with the corresponding function key will automatically setup the waveforms based on the inputs of the channels to the scope module. This will automatically determine the input signal range for all channels that are turned ON and evenly space the waveforms lines on the screen. These can be manually adjusted to a technician’s preference.
Trigger Point The trigger point is the point at which the waveform pattern starts on the scope screen. Setting the trigger point stabilizes the waveform pattern and prevents it from walking or oscillating across the scope screen—making it difficult to analyze. The trigger point can be adjusted individually for each channel that is turned ON to any point vertically and horizontally on the scope screen. To turn ON and adjust the trigger point for a waveform pattern press the function key that corresponds with “Trigger”. Page 25
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Trigger Adjustments Once selected, the column on the left of the screen will display trigger “Off”. Pressing right on the directional key turns the trigger “On”. When turned “On”, an indicator on the waveform pattern appears. This shows the location of the set trigger point.
Trigger Position Indicator
We can change the waveform to show the input signal either increasing or decreasing from the set trigger point by highlighting the box below the “On”. Pressing left or right on the directional key changes the trigger slope to either “Rising” or Falling”. Once “Rising” or “Falling” has been chosen and still highlighted, pressing down on the directional key removes the highlight from the trigger slope selection and brings up a crosshair on the scope screen. The intersection of the crosshair represents the position of the trigger point. Using up, down, left and right on the directional key adjusts the position of the trigger point in any position vertically and horizontally on the scope screen. Time and voltage values of the trigger point are displayed in the lower portion of the left column.
No Highlight
Trigger Point Crosshair
Trigger Point Position Values
Page 26
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
CURSORS Cursors allow you to determine amplitude, frequency and time measurements of live and paused waveform patterns. By selecting “Cursors” with the left function key, you have the option of using “Horizontal” or “Vertical” cursors.
Horizontal Cursors Horizontal cursors can be used to determine the amplitude of an input signal. The two cursors can be positioned individually to any point on the waveform pattern. Highlight the desired cursor you wish to move, this will be shown as a solid line on the scope screen when selected, then use the left and right directional keys to move the cursor up and down on the screen. To change between cursor 1 and 2, press up or down with the directional key. The position value of the cursor in volts or amps, depending on the input, will be shown in the highlighted area. The difference in value between both cursors will be displayed below the highlighted cursors.
Highlighted Cursor
Cursor Position Values Page 27
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Vertical Cursors Vertical cursors can be used to determine the time measurement of an input signal. The two cursors can be positioned individually to any point on the waveform pattern. As with the horizontal cursors, highlight the desired cursor you wish to move, this will be shown as a solid line on the scope screen when selected, then use the left and right directional keys to move the cursor left and right on the screen. The position value of the cursors, in Time, will be shown in the highlighted area. The distance in Time between both cursors will be displayed below the highlighted cursors. Also, the frequency of a repetitive signal will be displayed in the same area
Cursor Position Values and Frequency Reading
Page 28
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
SAMPLE WAVEFORMS Magnetic Wheel Speed Sensor
Good Waveform V 10 8 6 4 2 0 -2 -4 -6 -8 -10
0
10
20
30
40
50
60
70
80
ms 90
Bad Waveform V 10 8 6 4 2 0 -2 -4 -6 -8 -10
0
10
20
30
40
50
60
70
80
ms 90
Voltage output of sensor too low
Page 29
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Hall Effect Crankshaft Position Sensor
Good Waveform V 15.0 13.5 12.0 10.5 9.0 7.5 6.0 4.5 3.0 1.5 0.0
0
1
2
3
4
5
6
7
8
9
10
Bad Waveform V 15.0 13.5 12.0 10.5 9.0 7.5 6.0 4.5 3.0 1.5 0.0
0
1
2
3
4
5
6
7
8
9
10
No start Condition Sensor signal is not being pulled to ground Possible faulty sensor or poor ground to sensor
Page 30
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Engine Coolant Temperature Sensor (As engine warms up )
Good Waveform V 5.4 4.8 4.2 3.6 3.0 2.4 1.8 1.2 0.6
0
0.0
0
50
100
150
200
250
300
350
400
450
S 500
Bad Waveform V 5.4 4.8 4.2 3.6 3.0 2.4 1.8 1.2 0.6 0.0
0
0
50
100
150
200
250
300
350
400
450
S 500
Sensor has an internal short to ground at a certain temperature
Page 31
Body Electrical Specialist : Electrical Diagnosis And Repair – Waveform Analysis
Mass Airflow Sensor (At Idle)
Good Waveform At Idle V 15.0 13.5 12.0 10.5 9.0 7.5 6.0 4.5 3.0 1.5 0.0
0
1
2
3
4
5
6
7
8
9
10
8
9
10
Bad Waveform At Idle V 15.0 13.5 12.0 10.5 9.0 7.5 6.0 4.5 3.0 1.5 0.0
0
1
2
3
4
5
6
7
Faulty Mass Airflow Sensor
Page 32
