LAB SCOPES AND ACCESSORIES
Scopes have been used to diagnose issues in vehicles for many
years. The first ones that were used were the “big box” oscilloscopes
used to analyze ignition systems. Later, features were
added to test batteries and test for resistance using voltmeters
and ohmmeters. Some other testers added fuel pressure and
vacuum gauges for additional capability. Further improvements
incorporated digital technology into their testing ability,
which allowed technicians to obtain more data quickly in order
to analyze issues. The other benefit of digitizing the data was
having the ability to store data and images in order to compare
test results with either known good, or known bad, test images.
These oscilloscopes were very useful, but not unlike today,
many of the features were not utilized by the technicians using
the tool. The good news is there have been quite a few improvements
to the tools, including more channels and tutorial features
included in many of the newer lab scopes.
In addition to tutorials, there are many how-to videos and
comparative waveforms available from various resources that
may assist a technician to both connect a scope and information
based on test results to determine what the issue is on the vehicle.
There are now many accessories available along with information
on how to test individual components with these accessories.
Some of the most popular accessories and their uses are:
• Inductive pick-up probes for RPM signals are very good
for quickly analyzing signals that sync to a specific event,
such as checking an ignition event compared to the actual
crankshaft position.
• Pressure transducers for measuring vacuum and pressure
can be used to analyze each cylinder’s pressure throughout
its cycle and compare it to other cylinders on the vehicle,
or known good vehicles. This type of test can easily determine
if an individual cylinder has a problem, or if there
is something like a timing belt issue, affecting all of the
cylinders. Tests with transducers can also be conducted
in the intake or exhaust systems to determine if there are
pressure pulses that could be an indication of an internal
mechanical issue with the engine.
• Current clamp probes, both for high and low current
applications, can be a great asset for your lab scope. Using
a current clamp allows you to connect to a circuit without
cutting or piercing the wires. Observing a waveform with a
high amp clamp is useful for checking starting and charging
systems. By adding an inductive pickup on the number
1 cylinder, you can use a waveform to perform a cranking
test showing relative compression. Low current probes are
useful for checking for irregularities in fuel pump current,
fuel injectors or primary ignition waveforms.
Another relatively new addition to lab scopes is software and
hardware for Noise, Vibration and Harshness (NVH). Using
this feature, a technician is able to place probes throughout the
Using the Noise, Vibration and Harshness (NVH) feature, a technician
is able to place probes throughout the vehicle and analyze waveforms
to pinpoint the source of noise or vibrations. This can be very helpful in
saving time locating intermittent or inconsistent issues.
vehicle and analyze waveforms to pinpoint the source of noise
or vibrations. This can be very helpful in saving time locating
intermittent or inconsistent issues.
During the last few years, technology has been able to reach
many more technicians by both reducing the size of the tool
and by adding features such as self-setting or auto-set.
One benefit to smaller lab scopes is the transition from
larger standalone devices to software accessible via apps for
tablets and phones. These advancements have provided many
more technicians the ability to obtain a single- or dual-channel
scope, maybe without all the features of a full-sized one, but
due to their relatively low price, they are able to see the value
of using a scope in their diagnostic process.
Auto-set features have allowed techs without much experience
using lab scopes to quickly connect and use them for diagnosing
issues. In my opinion, both smaller scopes and auto-set
features will pave the way for technicians to use scopes more
often and purchase larger full-feature scopes.
This Fluke pressure
transducer is a helpful
accessory for use with a lab
scope or DMM.
Continued on page 70
A useful lab scope accessory,
inductive pick-up probes for
RPM signals are good for quickly
analyzing signals that sync to a
specific event, such as checking an
ignition event compared to the actual
crankshaft position.
www.VehicleServicePros.com OCTOBER 2017 PROFESSIONAL TOOL & EQUIPMENT NEWS 69
/www.VehicleServicePros.com