The ECT light is for the electronically controlled transmission. This type of trans. Has two modes, power or (pwr) and normal (nml). Located somewhere on the center console or dash will be a switch marked " ECT" throw the rocker one way and PWR illuminates, back the other way and " NML" will come on. Basically, power mode will delay shifts to a higher rpm and normal will go to the next gear much sooner, (lower rpm) for the same speed and throttle position.