An automobile transmission repair man who was found to have conducted "predatory business practices" while on probation for a similar consumer fraud was ordered yesterday to serve a one-year prison term.

The man, Riley T. Ferebee, operated the Automatic Transmission Sales and Service firm at 4312 Rhode Island Ave., Brentwood, until it was shut down about two weeks ago by the Prince Georges County Department of Licenses and Permits. It was the first business to be ordered closed by the consumer protection section of that department, investigators said.

Ferebee was convicted in federal court here in 1972 of fraud in the operation of his transmission repair business, and served about three months in prison before being released on probation. Yesterday, U.S. District Judge Barrington D. Parker ordered that probation revoked and ordered Ferebee to serve the additional 12-month term.

U.S. Magistrate Henry H. Kennedy Jr. made the recommendation that the probation be revoked after hearing numerous customers of Ferebee testify he had improperly repaired their cars, raised prices on repairs without informing them, and refused to honor warranties.

One man testified that a new battery was taken from his car while it was at Ferebee's business, and replaced with an older one. He said he discovered the switch when one of Ferebee's repairmen used the customer's own battery to "jump-start" the customer's after the customer's car wouldn't start.

Assistant U.S. Attorney Ann P. Gailis said the government wanted Ferebee sent to prison to "deter other deliberate consumer fraud artists." She described Ferebee's violation of his probation as an "arrogant criminal act."

The head of the U.S. Attorney's Office fraud division here, Robert W. Orgen, saidd the Ferebee case was only the second in recent yars in which a defendant's probation was revoked in a fraud-related case.

He praised the work of the Prince George's County consumer protection laints against Ferebee.