In 2005 Ambrose signed his deal to compete under NASCAR and Ford Motor Company signed Ambrose to participate overseas in the United States with Wood Brothers/JTG Racing in the NASCAR Camping World Truck Series in 2006 to start his career. However, Ambrose had to wait until part way through the 2006 season to begin. NASCAR did not clear Ambrose to race the NCTS' first three races, as they were held on intermediate to high-speed ovals, and like fellow Wood Brothers/JTG Racing driver Bobby East, Ambrose was not cleared to start in the faster races. Ambrose made his Truck Series debut on 1 April 2006 at the Kroger 250 at Martinsville Speedway, qualifying 20th and finishing 33rd after being caught up in an incident unfolding in front of him.