Getting Started
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2
The original on-board diagnostics (OBD I) lacked consistency in communica-
tion and interface while allowing different interpret ations amongst vehicle man-
ufacturers. Ford and Chrysler used different t ypes of engi ne control computers
and data link connectors, and GM varied the trouble codes and communicati on
protocols from year-to-year.
The tables below highlight changes for GM, Ford, and Chrysler. If this seems
confusing; don’t worry. Your tool makes it easy. Based on th e VIN information
selected during Scan Tool setup, the processor i s automatically rec ognized. All
you have to do is choose the correct adapter cable and jumper wires (if nec-
essary). Details on adapter cables and jumper wires may be found in “Diag-
nostic Link Connectors (DLC)” on page2-3.
GM On-Board Diagnostics
System Years Description
OBD I Control Module
1981–1995
Most vehicles used the 12-pin ALDL (Assembly Line Data Li nk)
located under the dash on the driver side. Some 94-95 vehicles
used the 16-pin OBD II (J1962) data link connector (DLC), but
use the Historical application software. Refer to the vehicle’s
Vehicle Emission Control Information label.
OBD II Control Module
1994*-Present Complies with OBD II regulations and uses the J1962 DLC.
* OBD II system used in certain 1994-1995 vehicles equipped with a 2.2L, 2.3L, 3.8L, 4.3L or 5.7L engines.
Ford On-Board Diagnostics
System Long Name Years Description
MCU
Microprocessor Control Unit 1980 –1991 Used in police vehicles, containing carbureted
engines. Uses the MCU DLC.
EEC-IV
Electronic Engi ne Control,
Fourth generation 1984 –1995 M os t Fo rd ve hicles e quipped with North American
engines. Uses th e EEC-IV DLC.
MECS
Mazda Electroni c Control
System 1988 –1995 Vehicles equipped with Mazda-sourced engines.
Uses MECS 6-pin and 17-pin DLCs.
EEC-V
Electronic Engi ne Control,
Fifth generation 1994* – present Complies with OBD II regulations and uses the
OBD II J1962 DLC.
PTEC
Powertrain Electronic Con-
troller 2000 – present Complies with OBD II regulations and uses the
OBD II J1962 DLC.
* EEC-V OBD II system used in 1994-1995 vehicles equipped with a 3.8L or 4.6L engine.
Chrysler On-Board Diagnostics
System Long Name Years Description
SMEC
Single Module Engi ne
Controller 1989–1990 Used a 6-pin Serial Communication Interface (SCI) DLC
and has bidirectional capability.
SBEC
Single Board Engi ne
Controller 1989*–1995 Used two types of DLCs: a 6-pin SCI and a 6-pin LH
series.
The first to allow a tool to reset the EMR light on trucks.
OBD II
PCM
OBD II Powertrain
Control Module 1995**– present Complies with OBD II regulations and uses the OBD II
J1962 DLC.
JTEC
Jeep/Truck Engine
Controller 1996– present Complies with OBD II regulations and uses the OBD II
J1962 DLC.
The JTEC system is used on light-duty trucks and Jeeps
* In 1989, the SBEC system was installed in selected vehicles with 3.0L V6 engines.
** Some vehicles in 1995 were equipped with the OBD II PCM.