CDK said on Monday it anticipates all dealers to be live on its dealer management system (DMS) by late July 3 or early morning on July 4.
The company, which provides software to car dealerships, had briefly shut down all its systems in June, saying it was investigating a cyber incident.
"We are continuing our phased approach to the restoration process and are rapidly bringing dealers live on the dealer management system," CDK said.
CDK also said its customer care channels had been restored and it was "actively working" on bringing other applications live.
The company had said last week it brought two small groups and one large publicly traded group of auto retailer live on DMS as part of its phased approach.
The outage had forced some U.S. auto dealers to revert to manual paperwork as the car industry technology and software provider worked to restore systems used by more than 15,000 retail locations in the country.
Industry experts have forecast slower growth in second-quarter U.S. auto sales as dealers struggled to access crucial software due to the disruptions at CDK.
"Although the impact of these attacks will be different from dealer to dealer, this event is another speed bump on the automotive industry's long road to recovery," said Jessica Caldwell, head of insights, Edmunds.
The cyber attack impacted about half of Volkswagen dealers and around 60% of Audi's dealers in the United States, Reuters had reported in June.
