Ashley Judd -- Wynonna Judd Put a Tracking Device on My Car!

Wynonna Judd is being accused of attempting to secretly track her sister Ashley Judd's every move ... by placing a GPS tracking device on her car.

The incident was first reported to police back in November when Wynonna's daughter drove Ashley's car to a mechanic ... and asked them to check for a tracking device -- according to reports.

The GPS device was located ... so they reported it to police -- and an investigation was launched to figure out who put it there.

According to the police report ... when cops contacted Ashley asking if she had any idea who placed the device on her ride -- Ashley pointed the finger at Wynonna.

Detectives tried in vain to reach Wynonna ... so they contacted the P.I. to whom the device was registered -- but they got the cold shoulder.

Wynonna's lawyer eventually called police -- and said the whole thing was a misunderstanding ... the singer was just trying to track her daughter whom she knew had been driving the vehicle.