User's Manual

1
1. Introduction
1.1 Background
The days of diagnosing and repairing automobiles without a laptop
beside you are quickly fading. Newer vehicles include a large number of
onboard computers that are each dedicated to performing specific tasks.
Common onboard computers in newer vehicle include the Engine
Control Module (ECM), Transmission Control Module (TCM), Fuel
Injection Control Module (FICM), Anti-lock Brake System (ABS),
Body Control Module (BCM) and numerous other control modules to
manage every electronic system from power door locks to crash data.
Each onboard computer is programmed at the factory with software
enabling it to perform certain tasks. Inside the ECM is software
containing hundreds or even thousands of parameters to control spark,
fuel, idle, cruising, emissions, economy, drivability, and performance.
Likewise, a TCM will have software to control how the transmission
and torque converter function. Sometimes, after the vehicle is shipped
from the automaker, updates are released to improve emissions, fuel
economy, drivability, performance, or specific bugs in the original
software that have caused warranty issues. Updating this software can be
a proactive fix because often it will resolve problems that a customer
hasn’t reported or noticed yet.
The practice of updating software in these modules is more commonly
known as flash reprogramming. At new car dealerships, flash
reprogramming is relatively straight forward because service technicians
are connected to the automaker and have the expensive, specialized
dealer service tools dedicated to reprogramming. The independent repair
shops have faced a more difficult challenge because most shops
typically service more than one make of vehicles. This increases the
complexity, cost and training required to operate dozens of different
factory service tools.
1.2 J2534 - A Solution Arrives
In 2000, the Environmental Protection Agency (EPA) had been
watching this issue and decided to take action. The EPA requested a
standard be developed within the SAE that led to J2534, a mandated