When car manufacturers started using computers to operate engines, software updates became part of a tech's job. At first,
updates were accomplished by replacing a memory chip in the control unit or the control unit itself. But by the time on-board
diagnostics two (OBDII) was introduced, most powertrain control modules (PCMs) could be reprogrammed.
Emissions-related software updates were available to the aftermarket, as required by the U.S. Environmental Protection Agency
(EPA), but they could be installed only with a manufacturer-specific tool. Because the EPA wants the aftermarket to be able
to perform all types of emissions-related repairs and they cannot require shops to purchase specific brands of tools, they
turned to the Society of Automotive Engineers (SAE) and the tool and equipment industry for an answer. The result was a universal
communication protocol defined by SAE Recommended Practice J2534.
PHOTO ILLUSTRATION COURTESY: MICHAEL STASSUS
|
The communication protocol, later revised to J2534-1, is a translator that allows a personal computer (PC) to communicate
with the PCM on all makes and models. The translation software is contained in a separate piece of hardware that connects
to a PC and to the OBDII port. It is not a computer or scan tool, but a pass-through device that enables a PC to interrogate
and install software into the PCM's permanent memory.
Once this tool became available, the EPA enacted a rule requiring all manufacturers to make their PCM update installation
software run on a PC using the Microsoft Windows 2000-or-later operating system. The rule also requires the updates and installation
programs to be available through the OEM's information Web sites, either as a downloadable program or on disc, "at a reasonable
price." The rule applies to 2004 and later model-years and only requires access to software that affects emissions. However, some
automakers have extended coverage as far back as 1993, and some allow reprogramming of non-emissions related control units.
Getting started
The typical J2534 pass-through tool is about twice the size of a deck of cards.
|
An OEM Web site logon is needed to purchase the installation program and the software update, and the prices vary quite a
bit. For instance, Toyota sells a "calibration CD" for $55, and it has the most recent calibration files for all models, all
applicable service bulletins and the Update Wizard installation software.
The disc can be purchased by part number and is available to registered members of Toyota's Web site. Registration is free.
It's certainly a "reasonable price," but the information on that disc is updated as it becomes available. Because all versions
of the disc bear the same part number, there's no way to know if a disc purchased last month is still current. It would be
safe to purchase a new disc for each job.
General Motors' (GM) aftermarket "reprogramming kit" is available through the Vetronix Web site, makers of GM's Tech II scan
tool, as well as from GM's subscription-based service information Web site. The kit lists for more than $1,000, but it includes
a CD with all installation software for all control modules on all models back to 1993, plus a one-year Web site subscription
to the most current software updates.
