The final rest position of an internal combustion engine crankshaft (16) is determined by counting pulses of a CRANK signal responsive to crankshaft rotation after engine turn-off (48) and evaluating the timing of the pulse edges to detect reversals in the direction of crankshaft rotation (40, 50, 54, 56). Times are assigned to a given edge of each CRANK signal pulse (40), and a ratio of specified time intervals (50) is compared to a threshold (54, 56) to detect crankshaft rock-back (62, 64) for controlling the pulse count direction (58).