The nation's colleges need brushup courses in basic ehtics, a Carnegie Foundation report suggested yesterday.

Citing "certain signs of deterioration" in academia, the foundation's Council on Policy Studies in Higher Education catalogued widespread "negative behavioral traits" among students, teachers and administrators alike.

"The basic problem may be bigger than the sum of its component parts," the report said, " a general loss of self-confidence and of a seanse of mutual trust, and a general decline in integrity of conduct on campus."

The signs include some abuses known for years, with new twists.

Nearly half the students Carnegie surveyed in 1976, or 47 percent, believed successful student had to "beat the system" to make it. Nearly 9 percent said outright cheating was needed to get good grades, while 66 percent said they thought it was possible to get good grades without really understanding the material.

Going modern, students have taken to stealing computer time and altering printouts. A Wayne State University student, the study said, "learned the password for a university research project and charged $2,000 worth of computer time to it."

Instead of taking notes, students often just take the book. Fully 80 percent of the colleges surveyed report that mutilation and theft of library materials is a major problem. The University of Maryland said 30,000 books are missing, while the University of California at Berkeley lost 18,000 books in three years at an average cost of $10 per book.

Students indignantly condemned occasional light penalties given book thieves, but when asked whether they would report a cheat or book theif, 75 percent said no.

Some students use college loan program like a bank, the report said, attending long enough to get some money and then dropping out. Fully 44 percent of veterans' loans are in default, 17 percent of the national disappeared without paying and 21,800 students have avoided payment by filing for bankruptcy.

Many of those students undobutedly feel cheated by the colleges. The survey found that 81 percent of the institutions checked supplied either inadequate or misleading information in their school catalogues. Colleges desperate for students have been caught trying to appear exclusive; course offerings dangled in front of prospective graduate students have disappeared after the registration fee was paid.

Students bothering to research the schools of their choice might have learned about some of these things, the Carnegie report said, but many do not bother. In fact, it said, students often resist learning about college they plan to attend.

"One rationale is fear . . . they are afraid to vetnture away from familiar turf," the study showed. Others seems dazzled by prestige school names and refuse either to believe negative reports or to consider any other institution.

The council recommended massive education efforts for students on their college rights and obligation; ethics codes, grievance procedures, strict enforcement and full disclusure polices for colleges and greater attention to accreditation procedures.

Otherwise, the study said, the coming enrollment decline may "Lead some students to take even greater advantage of the situation-and to make some colleges even more reluctant to insist on ethical conduct by students and even more likely to engage in improper conduct themselves."