2002 Chevy Trailblazer

Hi, those sound like throttle actuator codes. the throttle body on your vehicle should be an electronically controlled unit without wires to control actual acceration an deceleration. now, there is also an electronic switch called a potentiometer on the gas pedal that transmits signal to the throttle body to tell it what to do. most of the time, the throttle body is what goes bad here. you should also check the wiring to the unit for bad connection by wiggling the wire connector and seeing if the reduced engine power light comes on. if this happens, you will likely have to replace the wiring pigtail and the throttle body. but, in some cases, the gas pedal switch goes bad, and likely what is not allowing the transmission to shift out of park, the pcm may lock out the solenoid controlling the shifter. but, don't just run with that answer, it maybe completely wrong. i have seen more throttle bodies and wiring harnesses go bad than gas pedal switches in those vehicles. but you might want to have a shop diagnose further, it may even be two unrelated problems, or in the powertrain computer itself.