Nearly 5,000 employees and their families enjoyed the day with vendors, bouncy houses, food charities and pet adoption agencies.
Last year, the site was originally planned for a metal hydrogen plant, but that company has since backed out, leaving the space now vacant.
About 100 United Auto Workers members at Dakkota Integrated Systems rejected the company's "last, best and final" contract offer in a vote earlier this month.
Officials shut down Chamberlain Lane at North Winchester Acres during the investigation.
Dunn said the move is due to parts-related issues and should only last less than a couple of weeks.
Even as it invests billions in electric vehicles, Ford Motor Co. is also ensuring that its gas-guzzling cash cows keep rolling off the line at Louisville’s Kentucky Truck Plant for many years to come.