You don’t have to be Microsoft A+ certified to flash reprogram automotive PCMs, but the process requires a certain amount of know-how as well as special tools and access to the latest OEM software upgrades (which are not free!). What’s more, it’s not a risk-free endeavor. Certain precautions must be undertaken before you begin, and there are pitfalls that can trip up even those who are experienced in this sort of service procedure.

Like any laptop or desktop computer, the powertrain control module (PCM) in a car or truck contains a software program that tells it what to do. The software tells the PCM how to process its various sensor inputs and other requests so the vehicle operates normally. This includes all the things the PCM controls such as spark timing, fuel mixture, various emissions functions (EGR, EVAP, PCV, etc.), transmission shifting and torque converter lockup (unless these jobs are handled by a separate transmission control module), theft deterrence and self-diagnostics (including OBD II monitors and self-test procedures). The software may also include information on how to handle communications from other onboard modules such as the ABS/traction control/stability control system, climate control system, body controller, air bag module, keyless entry system and so on.

There are a lot of lines of code in the programming, and the instructions include calibration information designed for a specific vehicle applica...