what and where is the ECM to reset

You can try negative battery cable and leave off for 5 minutes and hook up and drive for a bit and if it persists you need to go to mechanic and they will OBD it and erase code if able or it could be a code that needs parts changes. ecm can cost lots if required but get second hand from wrecker you will save 300-600 that way. some ecms are 1000$ retail shop. most auto stores will obd for free and give you read out so you know what exactly it is.

ECM is under center console before pulling cable from chattery Get a code saver at auto zone cheap lighter plug kepts code For alarm and also radio Replace Cable ends if needed replace wait a few min.before Hocking up done.if still problem ECM replace get number from old unit To many different models to chose use old numbers