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OBD through the Ages

by Patrick on November 29, 2011

The OBD, or On Board Diagnostic computer is what ties all of the electrical and emissions systems together in a car, and it’s come a long way since its invention. You might have noticed the check engine light or low gas light turn on when you look at your car’s dashboard. Before the OBD computers, one of the most common signs that something was wrong was smoke billowing from under the hood or a general loss of cooperation from the vehicle.

The catalyst for the original OBD computers was fuel injection. Volkswagen in 1969 and later Datsun needed a way of fine tuning the fuel injectors with a higher degree of accuracy. Their actions were followed in 1980 by General Motors, who began to install its proprietary Engine Control Module. The ECM controlled the fuel mixture, ignition timing, and idle speed. Very shortly after, the Cadillac line started to come equipped with a diagnostics system that provided error codes and sensor data right on the dashboard.

In 1988, the Society of Automotive Engineers standardized the diagnostic connector port and signals to make OBD maintenance more consistent across brands. Following suit, the California Air Resources Board three years later requires OBD systems on all vehicles made in 1991 and after.

In the mid 1990’s, the OBDII specification came about and became mandatory for all new vehicles after 1996. The OBDII standard includes a much larger list of diagnostic trouble codes. It also standardized output codes allowing scanner tools to read codes from any vehicle with OBDII installed.

Since many companies designed their own software originally, they have been reluctant to standardize. This has resulted in many different formats of software. This makes matters rather difficult for both mechanics and product developers. Mechanics are still able to read many codes, but the ability to make changes requires very expensive specialized equipment.

Product developers must learn to work with every manufacturer’s software in order to assure that new products work with any car that needs it. And just like learning new languages, it takes large amounts of time and effort.

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