Autodata - Diagnostic Trouble Codes Fault locations and probable causes - 2004 edition

Trouble codes
If the trouble code is greater than 9, long flashes are used
for the tens and short flashes for the units. For example
- Fig. 5 shows one long flash, and two short flashes
Fig. 5
separated by a short pause, indicating trouble code 12.
In 1988 the California Air Resources Board (CARB)
introduced legislation covering all new cars sold in
California. These new laws governed on-board diagnostic 1 2
--
requirements for emissions related faults and began the
process of standardization in the US and eventually
Europe.
These regulations were known as onboard diagnostic
systems - phase I (OBD-I) and were subsequently
adopted by the vehicle manufacturers, for states other
than California.
The basic requirements of OBD-l were as follows:
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A malfunction indicator lamp (MIL), to provide a visible
warning that an emissions related fault had been logged
by the engine control module (ECM).
Provision for the logging and storage, for subsequent
retrieval, of diagnostic trouble codes (DTC)/flash codes for
emissions related faults.
The location of the diagnostic socket, the method of
access to the trouble codes and the configuration and scope of the self-diagnosis was left to individual vehicle
manufacturers.
This resulted in an almost complete lack of standardization, requiring the technician to adopt different procedures and to
use different equipment for each vehicle.
In 1995 the California Air Resources Board (CARB), after consultation with the Society of Automotive Engineers (SAE),
introduced further legislation covering all new cars sold in California.
These regulations are known as OBD-ll and have been adopted for all states. They closely define trouble code logging
and retrieval. More significantly they require monitoring of the operation of the system and components, in addition to
detecting component failures.
OBD-ll also covers systems other than engine management.
Basically the US OBD-II regulations have been adopted for European vehicles and are known as EOBD - European On
Board Diagnostics.
These EOBD regulations became mandatory for most new petrol engined vehicles produced after January 1 st 2000
(diesel and LPG engined cars were not required to comply until 2003). Most petrol engined vehicles already in production
before January 1 st 2000 were granted exemption until January 1 st 2001.
EOBD codes
Basic requirements
Malfunction indicator lamp (MIL) located on the instrument
panel, which either flashes or illuminates continuously,
when a fault is detected. If no fault is present the MIL
Fig. 6
-
should illuminate when the ignition is switched on and
extinguish when the engine starts.
Standard configuration of 16 pin data link connector (DLC)
The 16 pins of the DLC are arranged in two parallel rows, 1-1-1111
with certain pin connections defined by the EOBD
regulations and the rest allocated by the vehicle
manufacturer -
Standard location for the DLC
The standard location for the DLC is defined as being
between the driver's end of the instrument panel and
300 mm beyond the vehicle centre line, accessible from
the driver's seat.
The recommended location is between the steering
column and the vehicle centre line.
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