iCarsoft HD I, User Manual

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Heavy Duty Diagnostic Tool HD I User’s Manual
model. SAE J1587 is used in conjunction with SAE J1708 for automobile
communication.
SAE J1939
SAE J1939 is the vehicle bus standard used for communication and
diagnostics among vehicle components, originally by the car and heavy duty
truck industry in the United States.
SAE J1939 is used in the commercial vehicle area for communication
throughout the vehicle. With a different physical layer it is used between the
tractor and trailer. This is specified in ISO 11992.
SAE J1939 can be considered the replacement for the older SAE J1708 and
SAE J1587 specifications.
SAE J1939 has been adopted widely by diesel engine manufacturers. One
driving force behind this is the increasing adoption of the engine Electronic
Control Unit (ECU), which provides one method of controlling exhaust gas
emissions within US and European standards. Consequently, SAE J1939 can
now be found in a range of diesel-powered applications: vehicles (on- and off-
road), marine propulsion, power generation and industrial pumping.
Applications of J1939 now include off-highway, truck, bus, and even some
passenger car applications.
2.4 OBD II Definitions
Powertrain Control Module (PCM) -- OBD II terminology for the on-board
computer that controls engine and drive train.
Malfunction Indicator Light (MIL) -- Malfunction Indicator Light (Service Engine
Soon, Check Engine) is a term used for the light on the instrument panel. It
is to alert the driver and/or the repair technician that there is a problem with
one or more of vehicle’s systems and may cause emissions to exceed federal
standards. If the MIL illuminates with a steady light, it indicates that a problem
has been detected and the vehicle should be serviced as soon as possible.
Under certain conditions, the dashboard light will blink or flash. This indicates
a severe problem and flashing is intended to discourage vehicle operation.
The vehicle onboard diagnostic system cannot turn the MIL off until the
necessary repairs are completed or the condition no longer exists.
DTC -- Diagnostic Trouble Codes (DTC) that identifies which section of the
emission control system has malfunctioned.
Enabling Criteria -- Also termed Enabling Conditions. They are the vehicle-
specific events or conditions that must occur within the engine before the