Professional_Tool_And_Equipment_News_September_2020 - 29

TOOLS USED:
* Scan tool
* Vehicle information
* Diagnostic smoke tester
* RRR machine
* Yellow Jacket ManTooth
* Digital Multimeter (DMM)
* Fuel pressure tester

scan tool can be used to look at Mode
$06 information to see which part of
the evap system malfunctioned. This is
done by observing the Mode $06 data to
see specifically which part of the evap
test failed, which allows you to learn
from your vehicle information system
about that aspect of the evap test process. You can then use that as a starting
point for your testing.
Your scan tool also has the ability to
control some features of the evap monitor test as well as monitor the datastream
to see if it's functioning. Many scan tools
will allow you to perform what is commonly known as a "Service Bay Test",
basically an electrical test of the purge
and vent functions of the system. Using
bidirectional controls and monitoring
various PID's, you will also be able to see
if the purge valve is opening and closing properly by monitoring oxygen sensor voltage, or, with some vehicles, fuel
tank pressure.
One of the best tools to help locate
evap system leaks is a diagnostic smoke
machine. Connecting a smoke machine
allows you to easily observe any trace
of smoke that would indicate a leak,
but in some cases, you will need to use
the smoke machine and a little ingenuity to find a leak. I have had multiple
vehicles that had a faulty purge solenoid which did not completely close,
thereby allowing the system to lose
pressure (vacuum).
Even though the system was still

p The Mity Vac Fuel tester displays pressure
and flow, which enables you to assure there are
no issues in fuel delivery.

closed to the atmosphere, the computer
system detected a leak. The way I tested
for a faulty solenoid was to connect the
smoke machine to the system, then disconnect the hose from the purge solenoid to determine if there was a leak.
A helpful hint for finding traces of
smoke, especially in a brightly lit shop,
is to wave a laser pointer around the area
of a suspected leak. The laser light will
highlight any faint traces of smoke.

ISSUE TWO:
HVAC SYSTEM ISSUES

With most modern vehicles using the
body control computer and the powertrain control module (PCM) to control
HVAC functions, a scan tool along with
your Recover/Recycle/Recharge (RRR)
machine is now necessary to fully diagnose any issues within the system.
First, check for any fault codes in
either the PCM, body control module
(BCM), or HVAC systems. If no codes
are present, connect your RRR machine
to the vehicle, and, if necessary, recharge
the system. Once you know the system
is properly charged, your scan tool can
provide you with valuable information
regarding zone temperatures, door
positions, and various other pieces of
information that can provide you with
diagnostic clues.
One tool that's been extremely helpful in quickly diagnosing "problem
vehicle" A/C systems is the Yellow
Jacket ManTooth Wireless Pressure/

www.VehicleServicePros.com

SEPTEMBER 2020

Temperature Gauge Automotive Kit.
It consists of a series of Bluetooth connected pressure and temperature probes
that allow an app on your mobile device
to not only monitor, but diagnose issues
based on temperature and pressure
while you are driving the vehicle. Not
only is this a ideal tool for for final test
drive verification, but is extremely valuable for intermittent issues, allowing you
to safely monitor system pressures and
temperatures while driving.

ISSUE THREE: FAULT
CODEP0420 - CATALYTIC
CONVERTER ISSUES

It may seem simple enough that if you
get a code for a faulty catalytic converter,
you should be able to replace the converter and be good to go, right? Not so
in most cases. You need to look at your
vehicle information database to determine what conditions need to occur in
order to set that fault code. Along with
the conditions, determine which sensors the computer is using to monitor
the system. Most vehicles will use O2
sensor data, both upstream and downstream, to monitor the exhaust to see if
the catalytic converter is doing its job.
Factors that prevent the system from
working properly include unmonitored
air in the exhaust stream (exhaust leaks),
faulty oxygen sensors, engine oil or coolant leaking into the intake, exhaust
fouling an O2 sensor or the converter,
or misfires.

PROFESSIONAL TOOL & EQUIPMENT NEWS

http://www.VehicleServicePros.com

Professional_Tool_And_Equipment_News_September_2020

Table of Contents for the Digital Edition of Professional_Tool_And_Equipment_News_September_2020