At General Motors Corp.'s training center in Fairfax, scores of auto mechanics and technicians are learning that the top U.S. auto manufacturer is now the nation's largest producer of computer components and installations.

"Overnight General Motors has become the biggest producer of control computers in the world," said GM's Washington public relations manager, Frank Faraone. "We make about 17,000 or 18,000 of these computers every day."

Is the automotive giant turning to electronics to weather the current car sales crisis? Hardly.

Late in the last model year GM introduced its computer command control (CCC) system into several models. New, 1981 model gasoline engine cars all carry the CCC system.

The complex system consists of a computer unit built into the car that is capable of monitoring several different engine functions and actively controls some others, most importantly the fuel-air mixture. For instance, on a cold day, the CCC automatically allows a richer fuel-air mixture into the carburetor for easier starts. The computer will also increase the air intake of an engine to account for an oxygen flow reduced by a dirty air filter. But when the filter becomes too dirty, CCC alerts the car operator by activating a "Check Engine" dash light.

A prudent car owner will take the hint and arrange a visit with his GM repairman. Then the diagnostic function of the CCC comes to light.

"I'm super-satisfied with the new computers," exclaimed Ed Orvos, a long-time instructor at the center. "We spent 10 years on the research and development of this thing and it's dynamite."

"And the reception from technicians has been excellent," added Ben Wescott, director of the facility.

The overall operation and use of the CCC is what auto mechanics from miles around come to Fairfax -- and GM's 30 other regional training centers -- to find out about.

They learn that by merely grounding the computer system, the "Check Engine" light will emit a flashing signal that corresponds to a basic diagnostic code listed in GM's new repair manuals. The computer has a built-in memory so that even if the problem that originally activated the warning light somehow corrects itself, the light will still flash the appropriate code and the problem can be checked, just in case. If more than one affliction is besetting the car, the CCC will flash as many codes as it takes to patch things up.

The computer command control system is the newest introduction of space-age technology into GM cars and the focus of the current training campaign.But a lot more goes on at the training center than just instruction in the nuances of the CCC.

GM opened the Northern Virginia center in August 1954 as an occupational tool available without charge to all auto mechanics. Classes in body work, electrical systems, power train operations, brake and suspension systems and other technologies are available. The only specific limitation to the courses is that all the work and demonstrations are done on GM cars.