Embodiments related to identifying a reference scan cell locationally related to a fault condition exhibited by a scan chain in which the reference scan cell is included are provided. A method for identifying a reference scan cell is provided, the method including, in a capture mode, outputting combinational logic values to scan cells in the scan chain so that scan cell values for the scan cells are based on respective combinational logic values, the combinational logic values electrically connected with the scan chain. The method further includes, in a shift mod, sequentially determining the scan cell value for each scan cell, and identifying as the reference scan cell a scan cell last determined to be at an expected logical state for that scan cell.