60 Auto Heating & Air Conditioning
information publishers provide technical support ser vices
over a technical hotline. Calling these hotlines will connect
you with a technical support person. Hotline personnel often
have information gathered from actual repair and diagnosis
situations. This is a way of obtaining real life information
that would otherwise not be available. Manufacturer hot-
lines will also have access to the latest update information
from manufacturers’ engineering departments.
Some vehicle manufacturers’ hotlines are available
only to the technicians who work for a manufacturer’s
dealership. Other hotlines are available by subscription.
These hotlines can be accessed after a yearly fee is paid.
Some parts manufacturers’ hotlines are available to anyone.
These hotlines are intended to help the technician who has
questions about the manufacturers’ parts.
Computerized Assistance
Advancements in technology continue to provide auto
technicians with new tools and resources. The availability
of electronic media and the popularity of information on
demand offer technicians many diagnostic and reference
source options.
Scan Tools
Scan tools retrieve computer trouble codes and
display them in a readable form on an LED or LCD screen,
Figure 3-44. The push-button keypad is used to select func-
tions and enter information. The fi rst scan tools were used
to display information about engine operating conditions,
such as coolant temperature and ignition timing. New scan
tools also access body and chassis computers to retrieve
information about non-powertrain accessories, including
the heating and air conditioning system.
Scan tools are connected to the vehicle’s data link
connectors, usually called DLCs. All vehicles manufactured
since 1996 have OBD II systems and use standard 16-pin
diagnostic connectors. This enables OBD II scan tools to
access the computerized systems of more than one vehicle
manufacturer through the electronic control module (ECM).
Modern scan tools may perform system checks by forcing
certain vehicle components to operate. This can help the
technician diagnose an intermittent performance problem
by taking a “snapshot” of the sensor inputs and computer
outputs while the problem is occurring. Some scan tools
also have built-in multimeters and waveform meters.
OBD II scan tools can be used to reprogram a vehicle’s
computer (ECM) from a central computer located at the
vehicle manufacturer’s service headquarters. OBD II scan
tools can be updated with new vehicle or system specifi ca-
tions by downloading the information from a CD-ROM disc
or an online source. Scan tools have become an essential
part of engine performance and automotive repair. Some
technicians even purchase scan tools for their own use.
Flasher Modules
Flasher modules allow a vehicle’s ECM to be updated
without using a scan tool. This allows a shop’s scan tool
to be used for other jobs while the vehicle is being repro-
grammed. The fl asher module is attached to the vehicle’s
data link connector and to a shop PC with standard
cables.
To reprogram a vehicle computer with a fl asher module:
❑ Attach the fl asher module to the vehicle DLC and the
shop PC, Figure 3-45.
❑ Access the manufacturer’s service information Web
site or insert the appropriate CD-ROM.
Figure 3-44. This scan tool can be used to retrieve trouble codes,
locate sensor and output device problems, and reprogram a
vehicle’s ECM.
Figure 3-45. Flasher modules create an interface between
the vehicle ECM and the factory data to allow the ECM to be
reprogrammed.