A vehicle diagnostic test sequence authoring module includes a flowchart display screen, an add node display screen, an expression builder display screen, a panel editor display screen, a phrase editor display screen, and a meter editor display screen. Each of the author module display screens include a combination of selectable fields, including editable text fields, dropdown menu fields, checkbox fields, selectable bullet fields, logical display buttons, and logical links, that facilitate development of diagnostic test sequences, represented by hierarchical flowcharts, by vehicle diagnostics experts who do not have substantial knowledge of a computer programming language. A flowchart includes multiple nodes, representing individual test steps, and branches that connect the nodes. Logical expressions based on vehicle test conditions determine the flow of the test sequence.