General_Information

General Information

This section describes the general Scope Multimeter control icon functions, screen layout and optional settings. The screen layout and control icon functions are shared between the digital/graphing multimeters and lab scope.

Scope and Multimeter tests are not vehicle specific, therefore vehicle identification is not required.

Images and screenshots in the following sections are provided as general reference only, and in some instances have been modified for clarity.

Main Screen

Toolbar—contains navigational and control icons

Main Body—contains the meter/scope display

Control Panel—contains channel/trace controls

Data Buffer Position Indicators—graphical and numerical position indicators

Expand/Collapse icon—toggles display between split and full screen views including the control panel

Main Body

The main body may display the following:

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Menu - Select from a menu using the touch screen or the control buttons.

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Meter/Scope Display - Up to two signal traces can be displayed simultaneously. Each trace is displayed as voltage over time and the voltage level is recorded on the vertical, or “y”, axis and time is presented on the horizontal, or “x”, axis of the screen.

Data Buffer Position Indicators

The graphing multimeter and lab scope functions have the capability to save, store and playback, data (signals) utilizing internal storage “buffer” memory.

The Data Buffer Position Indicators are used to visually see the overall amount and position of the of stored buffer data during saving and playback.

For additional information on the Data Buffer, Data Buffer Position Indicator and Saving, Storing and Reviewing Data files, see About the Data Buffer.

Control Panel

The control panel is common to all three Scope Multimeter functions, and contains the channel (or “trace”) settings and controls that are used to monitor and adjust the signal being measured. This section provides a general overview of all the channel settings and control features used across all three Scope Multimeter functions.

This section is intended as a general overview of the channel settings. Not all the settings or controls described in this section are applicable with all functions, some may be “grayed out” or not active (applicable) depending on the function or test. Function availability is noted as applicable.

The control panel can be toggled on/off by selecting the Expand/Collapse Icon to switch the screen between full and split test meter views.

Cursors

Cursors Icon

Zero Base Line Indicators

Control Panel—contains channel/trace controls and settings

Data Buffer Position Indicators—graphical and numerical position indicators

Icons

The following control icons are common across most Scope Multimeter functions, however use may vary depending on the active function or test. A yellow frame surrounding an icon (highlighted), indicates it is selected.

Icon	Function
	Pause - Pauses the data buffer
	Start (Capture) - Resumes active data collection.
	Zoom - Increases and decreases screen magnification. The zoom function is only available during data review (scope paused).
	Cursors - Toggles cursors on/off.
	Step Forward - moves to the next point in the data. To quickly step forward, select this icon then press and hold the Y/`a` button.
	Forward 1 Frame - allows forward movement by one frame. To quickly skip forward, select this icon (yellow frame appears around icon) then press and hold the Y/`a` button
	Step Back - moves to the previous point in the data. To quickly step backward, select this icon then press and hold the Y/`a` button.
	Back 1 Frame - allows backward movement by one frame. To quickly skip backward, select this icon then press and hold the Y/`a` button.
	Expand / Collapse - Toggles display of the control panel (Trace Detail).
	Save - Saves the data stored in buffer memory to a file.
	Tools - Open the Tools menu, providing options for scope and meter settings.

Lead Connection

Standard “safety type” test lead jacks are located on the top of the diagnostic tool, and are compatible with many test leads and probes . Insert the applicable test lead or probe terminal end into the jack to compete the connection.

To avoid damaging test leads, do not pull on the wire when removing the leads from their jacks. Pull only on the lead terminal end.

Ground Jack (Black)

Channel 1 Jack (Yellow)

Channel 2 Jack (Green)

General Reference

Basic Setup Tips (unknown signal type)

When conducting automotive diagnostics, situations may arise when you need to capture and analyze a signal that you are not familiar with, or know what the intended waveform pattern should look like, or even how to set the scope to acquire the signal.

The following tips are intended to provide guidance, at the most basic level to assist you in your lab scope diagnostics.

Testing information and/or procedures for testing certain components may be available in the Guided Component Test function. If you have already narrowed down the system and/or component to test, ID the vehicle within the Guided Component Test function, and check the available tests first, as this may save you some time.

If the Guided Component Test function, does not have the test you are looking for, you need to determine are few thing about what you are testing to get the scope / meter set up to capture a signal or make a measurement.

Testing information and known good waveform libraries may also be available from other sources (e.g. SureTrack, ShopKey Pro or other online sources). Obtaining correct testing reference information can be a key advantage in making sound repair decisions.

Listed below are a few basic questions to help narrow down the testing direction to follow.

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Are you looking to make or test a simple voltage or current level or maybe check resistance or continuity? Then you may want to use the DMM.

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Are you looking to check a circuit/component for an erratic dropout or make a frequency test? You may want to use the GMM.

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Do you need to see signal details (level, shape, frequency etc.)? The lab scope may be the best choice.

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Are you testing a DC or AC signal?

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What is the operating range of the circuit?

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Do you know what type or shape the intended waveform should be?

After answering the questions above, you need to determine which Scope / Multimeter test function you are going to use (e.g. Lab Scope, DMM or GMM).

Once your test function is selected, you can now connect the test leads and select the applicable probe and scales:

Connect the test leads or probe, to the applicable test point(s). Always use the correct lead or probe designed for the test and ensure the signal and ground connections are clean and secure.

For the initial setup, you may wish to turn other channel settings off (e.g. Peak, Filter, Invert, AC Coupling, Threshold etc.), as these may affect the signal display.

As a default setting, trigger is normally off. The scope/meter uses internal circuitry to display a signal if present. However, in certain circumstances additional channel adjustments may be required, or the trigger mode may have to be turned on, for a signal that is present but is not displayed. You may also need to readjust the vertical scale if set to low, in order to bring the signal into the viewable display area.

At this point you should have a visible signal on the screen. An ideal signal should be displayed within the area of the display.

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If the signal goes beyond the top and bottom of the display, try and readjust the vertical scale to a higher setting, to bring the signal into the viewable display area.

Use the zero baseline controls or move the zero baseline marker onscreen to move the zero baseline of the signal vertically on the screen to the desired position.

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If the signal cycles are compressed (close to each other), try and readjust the sweep scale (horizontal scale) to a lower setting to display less cycles.

Once you have a usable signal displayed, if needed use the trigger function to stabilize a changing or erratic signal (a signal that may flicker or drift), so that it is easier to view. Try and set the trigger at the mid-point of the signal, and then adjust as needed from there.

As all signals are different, and due to other variables, additional adjustments may be needed to get the signal displayed exactly how you need. Review the channel settings section in this manual for additional information on using the settings.

At this point you should have a signal displayed that will allow you to see the overall signal characteristics, and allow you to begin your diagnosis.

Comparing your captured waveforms to known good waveforms, can be a time saver and provide supporting evidence when trying to determine a fault. See Using Known Good Waveforms below for additional information.

Using Known Good Waveforms

In some cases captured waveforms may not provide enough information to determine if a suspected sensor or circuit is at fault. Comparing the test vehicle waveforms to known good waveforms, can help to provide supporting evidence when trying to determine a fault.

Known good waveform examples may be available from different sources including the Guided Component Tests function, information services (e.g. SureTrack) or from other sources.

One of the many resources available within the optional online version of SureTrack is the comprehensive collection of known good component waveform examples gathered through actual vehicle tests. Waveform and PID graph screenshot examples are provided by fellow member technicians and shared with all members in a searchable (vehicle/component specific) database.

As good practice, capturing waveforms before and after the repair will help you to build your own library of waveforms for future troubleshooting.

To find waveform examples within the SureTrack Community:

Visit the SureTrack website, and join SureTrack (if not already a member).

Enter (identify) the test vehicle details in the search field at the top of the screen.

Select the Dashboard tab (left side).

If waveform and/or PID graph examples are available, the Library tab will be displayed at the top.

SureTrack - Library tab showing list of waveform examples

Select the Library tab . A list of examples is displayed and sortable by selecting the PID Graph and/or Waveform check boxes at the top.

Search through the list and select the desired example.

Typical examples are shown below.

Examples may not be available for all vehicles or components and are supplied from various diagnostic tools. All examples are provided as reference only.

SureTrack - Waveform examples

For additional waveform reference information, visit the Snap-on Diagnostics forums to ask questions, and share information at

http://productforum.autorepairdata.com

Troubleshooting Signals

When capturing signals, you may occasionally encounter problems with the way the signal initially displays. Noise, hash, fuzz are some of the terms used to describe, unwanted signals displaying in or on the signal you are trying to capture, basically making the signal unclear. The following tips are intended to provide some basic guidance, to help resolve these types of issues if encountered.

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Make sure you have the correct test leads connected to the applicable test point(s) and test lead jacks on the diagnostic tool.

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Ensure the signal and ground connections are clean and secure, at the test points and diagnostic tool.

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Ensure the polarity of the test leads connections are correct.

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If using stackable connectors, try to isolate or only connect the leads being used to capture the signal.

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Make sure the ground lead is providing a direct ground from the circuit to the diagnostic tool test lead jack.

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Isolate the test leads from other components, leads, or systems that may induce unwanted noise into the signal being tested (e.g. electric motors, secondary ignition components, relays, alternators, etc.)

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Use the shortest test leads possible.

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Try different test leads, to verify the issue. Use the recommended snap-on leads or probes available for the diagnostic tool or equivalent. Shielded test leads are recommended.

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Check the test lead or probes for damage.

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Enable or disable channel controls also to help try and clean the signal:

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Peak Detect—maximizes sampling rate, but may pickup unwanted noise

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Filter—removes signal noise or interference

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Invert —switches signal polarity

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Coupling AC—blocks the DC portion of signal

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Threshold —provides a more accurate measurement on select GMM tests where noise is present

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Scale (Vertical scale adjustment)—adjusts vertical scale. Using a higher setting may provide a cleaner signal in some situations.

For signals that do not display or display off the screen, erratic, compressed etc.:

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Use a trigger to help stabilize the signal. Try and set the trigger at the mid-point of the signal, and then adjust as needed from there.

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If the signal wraps off the top and bottom of the display, try and readjust the vertical scale to a higher setting, to bring the signal into the viewable display area. .

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If the signal cycles are compressed (close to each other), try and readjust the sweep scale (horizontal scale) to a lower setting to display less cycles. Try a higher setting if the cycles are spread too far across the screen and seem flat.

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Move the zero baseline marker to move the zero baseline of the signal vertically on the screen to the desired position.

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Check calibration of test leads or probe(s) if applicable.

Units of Measurement / Conversions

Base Units
(Symbol) / Unit Prefix	Typical Expressions
(µ) micro	0.000001 or 10-6 or 1/1,000,000
(m) milli	0.001 or 10-3 or 1/1,000
(c) centi	0.01 or 10-2 or 1/100
(k) kilo	103 or 1,000
(M) mega	106 or 1,000,000

Electrical Units
(Symbol) / Description	Equivalents
(V) Voltage	V = I × R
(I) Current	I = V ÷ R
(R) or (Ω) Resistance	R = V ÷ I
(Hz) Frequency	ƒ(freq.) = 1 ÷ T(time) or 1 cycle per second
Voltage
(µV) microvolt	1 µV = 0.000001 V
(mV) millivolt	1 mV = 0.001 V
(V) volt	1 V = 1000 mV
(kV) kilovolt	1kV = 1,000 Volts.
Ohms
(mΩ) milliohm	1 mΩ = 0.001 ohms
(Ω) ohm	1 Ω = 1000 mΩ
(kΩ) kiloohm	1 kΩ = 1000 Ω
(MΩ) megaohm	1 MΩ = 1,000,000 Ω
Amperes
(µA) microamps	1 µA = 0.000001 amps
(mA) milliamps	1 mA = 0.001 amps
(A) amps	1A = 1000 mA
(ka) kiloamps	1 ka = 1000 amps
Frequency
(MHz) megahertz	1 MHz = 1,000,000 Hertz
(kHz) kilohertz	1 kHz = 1000 Hertz

Pressure Units
(Symbol) / Description	Equivalents
(psi) pounds per square inch	1 psi = 6894.757 Pa 1 psi = 0.06894757 bar 1 psi = 2.036021 inHg
(bar)	1 bar = 14.50377 psi 1 bar = 100000 Pa 1 bar = 29.52999 inHg
(Mbar) Millibar	1 Mbar = 0.001 bar
(Pa) pascal	1 Pa = 0.0001450377 psi 1 Pa = 0.00001 bar 1 Pa = 0.0002952999 inHg
(kPa) KiloPasca	1 kPa = 1000 Pa
(MPa) Megapascal	1 MPa = 1,000,000 Pa
(inHg) inches of mercury	1 inHg = 0.03386388 bar 1 inHg = 0.4911541 psi 1 inHg = 3386.388 Pa

Pressure Conversions
psi x 0.0689 = bar
psi x 6.8950 = kPa
psi x 0.0703 = kg/cm²
bar x 14.5030 = psi
bar x 100.0000 = kPa
bar x 29.5300 = inHg (60°F)
kPa x 0.1450 = psi
kPa x 0.0100 = bar
kPa x 0.0102 = kg/cm²
kPa x 0.295299 = inHg
kg/cm² x 98.0700 = psi
kg/cm² x 0.9807 = bar
kg/cm² x 14.2200 = kPa
inHg (60°) x 0.0333 = bar
inHg (60°) x 3.3770 = kPa
inHg (60°) x 0.0344 = kg/cm²
inHg x 25.4 = mmHg
mmHg x 0.003994 = inHg

Temperature Units
(Symbol) / Description	Conversions
(°C) degree Celsius	°C = 0.556 x (°F - 32)
(°F) degree Fahrenheit	°F = (1.8 x °C) + 32

Time Units
(Symbol) / Description	Equivalents
(µs) microsecond	1 µs = 0.000001 of a second
(ms) millisecond	1 ms = 0.001 of a second
(s) second	1 s = 1000 ms

Duty % to Dwell Conversions
Duty Cycle	Dwell
%	4 cyl	6 cyl	8 cyl
10	9.0	6.0	4.5
20	18.0	12.0	9.0
30	27.0	18.0	13.5
40	36.0	24.0	18.0
50	45.0	30.0	22.5
60	54.0	36.0	27.0
70	63.0	42.0	31.5
80	72.0	48.0	36.0
90	81.0	54.0	40.5
100	90.0	60.0	45.0

Glossary of Common Terms

Term / Abbreviation	Description
AC	Alternating Current - electrical current that switches polarity at regular intervals.
Aliasing	An effect that causes an incorrect signal to be displayed and/or causes a trigger to malfunction, due to the input signal exceeding the sample rate of the scope.
Amperage	The strength of an electric current, expressed in amperes
Amplitude	Vertical magnitude (level or position) of a signal, or the varying quantity from its zero value.
Buffer	An electronic reservoir for temporary storage of data
Cursor	Onscreen markers used to measure time, amplitude and frequency
Coupling AC	Function used to subtract the average value of a signal so that small variations can be displayed in the waveform.
DC	Direct Current - electrical current that flows in one direction only
Delta	Difference in time between two events.
Dropout	An intermittent or unwanted, vertical fall in a signal to zero that may cause an undesired result.
Duty cycle	Measurement of the length of a signals on time. Specified as a percentage (ratio), of the total cycle time.
Dwell	Used to measure a signals on time in degrees of dwell. Commonly used to measure mixture control solenoids on carbureted feedback engines and specified in duty cycle %.
Dwell 60	Measurement of the length of a signals on time displayed on a 0 to 60 degree scale. 0° = 0%; 30° = 50%; 60° = 100%.
Dwell 90	Measurement of the length of a signals on time displayed on a 0 to 90 degree scale. 0° = 0%; 45° = 50%; 90° = 100%.
Filter	Function used to filter or smooth out spikes and fast variations in signals.
Frequency	The number of times a signal repeats in one second. Measured in Hertz (cycles per second).
Glitch	An intermittent or unwanted, error in a signal that may cause a false or undesired result.
Grid	The graph displayed on the scope screen that is made up of the x and y axis scales that aid in the measuring of signal characteristics.
Horizontal Scale	See Sweep Scale
Invert	Function used to switch signal polarity,
Lambda (l)	Used to represent a numerical value denoting the actual measured air/fuel ratio with respect to the ideal air/fuel ratio at stoichiometry. Lambda equals one (1) when the actual air/fuel ratio is equal to the theoretical (stoichiometric) air/fuel ratio of 14.7 (14.66) to 1. Lambda less than 1 means excess fuel; greater than 1 means excess air.
Megasamples per second (MS/s)	Sample rate unit equal to one million samples per second
Noise or Hash	Unwanted voltage, current or signal interference that is imposed on a signal.
Parasitic Voltage	Trace voltage in a circuit after the main power source is disconnected.
Peak	The maximum amplitude value present in a varying or alternating voltage. This value may be either positive or negative.
Peak Detect	Peak detect captures and evaluates all signal sample points, in order to display fast occurring events or glitches.
Pressure Transducer	Electronic device that converts pressures (negative/positive) to electrical signals.
Pulse	A signal with abrupt (fast) signal direction changes in a positive or negative direction, with consistent level and duration.
Pulse Period	One complete on and off cycle or time period.
Pulse Train	Collection of signal pulses traveling together.
Pulse Width (duration)	Measurement of a signals on time in a circuit that pulses on and off. Specified in units of time.
Pulse Width Modulation (PWM)	A signal that continuously cycles on and off while the on-time varies within each cycle.
RMS	The RMS (root mean square) value of alternating currents and voltages is the effective current or voltage applied, rather than the peak current or voltage measurable. The AC RMS voltage value can be defined as the equivalent DC voltage of the AC voltage measured. RMS values are commonly used in AC electrical measurement, as they are more representative of DC measurements.
Sample Rate	Number of times (frequency) the scope/meter takes a sample of the signal. Specified in mega samples per second (MS/s).
Sampling	Process of obtaining a sequence of instantaneous values for a signal at regular or intermittent intervals. When a quantity of samples are collected the operational status of the device is determined.
Screen Update Rate	How often the captured data is (updated) displayed on the screen.
Signal	Detectable voltage, current, or magnetic field, by which specific information is transmitted in an electronic circuit or system.
Square Wave	A square or rectangular waveform (digital) which alternately switches high to low (on/off) for specific lengths of time, that has very fast rise and fall times.
Sweep Scale	The horizontal scale on the grid. Also referred to as time scale or x axis.
Threshold	The threshold function automatically sets a trigger and determines a threshold level in the middle of the signal range (calculated from the Min and Max measurements) to be used as a reference point to calculate the measurement.
Trace	The actual visible line displayed on the scope screen.
Trigger	A conditional function that initiates if and when a trace is drawn on the screen.
Trigger Slope	The slope that a trigger source signal must reach before the trigger circuit initiates a sweep
VAC	Volts Alternating Current
VDC	Volts Direct Current
Vertical Scale	The vertical scale on the grid or (y-axis) represents what is being measured (voltage, amperage, pressure etc.), and the unit of measurement it is being measured in.
Volt	Unit of electric potential difference.
Voltage	Electromotive force or potential difference, expressed in volts.
Voltage (inductive) Kick	A voltage, many times higher than the applied voltage, produced by the collapsing magnetic field in a coil when the current through it is abruptly terminated.
Waveform	The graphic representation (form) of a signal over time, which the trace displays on the screen.
Zero Base Line	Reference setting or 0% level of a graph scale.