Toni Carney begins her term on the Fairfax County School Board tonight, but the only difference it makes to her is that she finally has a vote.

Carney, a Burke Centre resident who moved to Fairfax in 1970, has been following the school board for the past five years. When the board stays after midnight at its long meetings twice a month, so does Carney.When the board appoints a committee to study an issue, Carney often chairs it. When the schools sought voter approval of $39.7 million in bonds this year for school construction and renovation, Carney helped lead the drive.

All in all, the 36-year-old Carney has been a self-styled ad hoc liaison between the 10-member school board and parents in the county who know about her active involvement in school affairs.

Her long experience ooffers some advantages.

"Technically, I'm supposed to have an orientation program set up for me," Carney explained. "But Superintendent (S. John) Davis told me his senior staff people said it would be crazy to waste the time and effort. They said there's nothing they could tell me I didn't already know.

"Always before I've been a lobbyist - working on lots of issues but ultimately trying to persuade school board members to vote a certain way. Now I've got a vote, and it's my turn to sit and listen to other people."

Carney, who replaces John J. Caussin on the board, will earn $4,500 a year as a school board member, but hopes she "won't go in the hole" paying for babysitters for her 3-year-old son.

Carney was first introduced to her present hectic schedule of three and four meetings a night through her interest in learning disabilities. She and her husband Patrick, a personnel specialist for the Treasury Department, discovered several years ago that their 11-year-old son suffered from a learning disability in mathematics.

She started "paying back" the extra time specialized teachers gave to her son by volunteering as a teacher's aide. Since then, she has served on the executive board of the Northern Virginia Association for Children with Learning Disabilities, where one of her accomplishments included selling $52,000 of exhibit space at the 1977 Conference for Children with Learning Disabilities for the organization.

Improving the quality of learning disability programs takes high priority with Carney, but she claims her interest in education is "much broader."

She says much improvement is needed in school board communication with parents, to translate "educational jargon into the English language."

"The way school officials talks about education is unintelligible to the average parent," Carney said. "It makes us look like we're hiding something. People think we're deliberately trying to make things sound obscure so they can't understand."

Carney also wants to see relations improve between the county Board of Supervisors and the school board, saying on that score, "we have nowhere to go but up." She also takes strong interest in developing minimum requirements for students to graduate, an effort she helped start in the county by serving on a task force that drafted requirements high school students should meet before graduating.

Unlike Caussin, who is a member of the Republican Committee, Carney is not active in politics. She said she had always voted as an independent during her career as a tax technician and a personnel management specialist for the IRS and when she began in 1967 to raise a family in Kansas City, Mo.

"I guess I have voted for more Republicans than Democrats since we've been in Fairfax," said Carney, who was nominated for the school board by Fairfax Supervisor Marie B. Travesky (R-Springfield).

Carney said she is not interested in using the school board as a springboard to political office."There's nothing about sewers and roads that interest me," Carney said. It would not have occurred to her to seek appointment to the school board, she said, if Caussin's resignation had not been so sudden and other citizen activists and political officials had not suggested she run.

Caussin announced last month he would not seek appointment to the school board, citing continued disagreements with Travesky as his reason.

"Volunteering had been enough for me for so long, a chance to get out and talk to adults about things other than houses and children," Carney said. Her many volunteer jobs have included serving as chairman of a task force studying Fairfax's declining school enrollment and chairman of the education committee of the Fairfax Federation of Citizens Association.

"Being on the school board is just a logical continuation of the work I've been doing all along," Carney said. "I've got the support of my family, that gives me the peace of mind to do it. And I've finally got the vote."