With its service manuals already about 120,000 pages long and expected to grow to 200,000 pages by 2000, General Motors Corp.'s Cadillac Motor Div. is testing Smart Mentor, a real-time mentoring program that guides technicians in repairing a car. Pilot models of Smart Mentor now are being tested at three Cadillac dealerships in Sarasota, FL, Troy, MI and Alexandria, VA.

Smart Mentor was produced by GM, the U.S. military, Raytheon/Hughes, Interactive Solutions, Inc. and the New Jersey Institute of Technology. The software is designed to be applicable in fixing everything from aircraft carriers to tanks - and even Cadillacs. The system includes a computer, worn by the technician, containing all the information in service manuals, and is combined with a speech-recognition module.

The latter allows a technician to free up his hands while he verbally requests the computer to guide him through the repair. John F. Smith, Cadillac's general manager, says the result will be faster, more reliable repairs and quicker return of customer cars dropped off for service. Best of all, no training is required to use Smart Mentor.

The software is commercially available from AT&T and is designed to work with a pentium-based computer and a Microsoft Windows operating system. The entire system fits into an Army canteen holder and Mr. Smith promises it will get smaller in the future. A flat-screen liquid crystal display is portable and has flexible legs on which the technician can easily rest Smart Mentor. Mr. Smith suggests that in the future the screen could be built into headgear or even eyeglasses.

At this time, Smart Mentor only has software to work on the Northstar V-8 system. Potentially it can be expanded into a tool for diagnosing every system in a car. Jim Roach, with GM's Service Technology Group (STG), gives a brief demonstration. Speaking into his headset, Mr. Roach coaxes Smart Mentor into locating a simulated problem within Northstar's ignition system. While eyeing the monitor in front of him, Mr. Roach softly steers the computer into revealing more precise information in a step-by-step manner, until the problem is diagnosed.

Mr. Roach says the skill level for auto technicians is higher than ever. But with Smart Mentor, technicians don't have to read and absorb so much printed material. He also notes that the same menu in Smart Mentor can be used by the military for its complex war machines. The military is actually working on a parallel program with GM to perfect Smart Mentor.

Mr. Roach emphasizes that GM is not committed solely to the technology: "It's the methodology we want to perfect," Mr. Roach says.