Abstract: A method and apparatus for real-time data stamping via datalink and volatile ECM timer/clock. An engine control module (ECM) includes a volatile time-keeping mechanism, such as time-keeping software code inserted into the ECM software, which is capable of keeping track of elapsed time as long as the ECM microprocessor is powered. The ECM initially sets the volatile time-keeping mechanism with real time (RT) at ECM power up by retrieving the current RT over an attached datalink from a non-volatile RT clock (i.e. a clock that keeps track of time even during ECM power down). Thereafter, the ECM microprocessor may time stamp stored data using RT from the volatile time-keeping mechanism. The present invention thus precludes the need to provide a dedicated RT clock for the ECM, or the need for the ECM to request RT over the datalink every time the ECM wishes to time stamp data to be stored.