She just wanted to teach her son right from wrong.

Single mom Tyeesha Mobley got so fed up when her 9-year-old took $10 from her purse that she called in the only people she could think of to set him straight — the NYPD.

At first the cops played along, with one telling her son, Tyleke, “You can’t be stealing. You’ll wind up going in the police car.”

But it got ugly when one of the officers got tired of the parent act — and blamed Mobley for being a bad mom in a racist rant that ended in her arrest, she claims in a Bronx lawsuit she filed against the NYPD and the city’s Administration for Children’s Services.

Mobley, 29, spent a night in jail and lost custody of little Tyleke and his kid brother for four months before a judge threw out the case against her.

Mobley, who filed the suit on Friday, said the scars still linger for her kids.

“They are really traumatized,” she said. “All my little one knows is the cops took him away from his mother.”

She hasn’t been back to work since the April 2014 incident and the three of them are in therapy.

Mobley expected better of the police when she arranged to meet them at a nearby gas station to show some tough love to Tyleke.

She said the cop who made the racist comments also roughed her up during the arrest.

Mobley is now taking courses in criminal justice.

“She’s raising her kids to be good kids. They’re respectful and polite,” said her lawyer, Philip Sporn. “This wasn’t the intended result.”