Thanks hmac300. Since that post I've had it to a highly recommended trans shop locally. They replaced the harness for the shift solenoids inside the pan (above the valve body) because after clearing the codes, it set those same codes immediatley without starting or driving the vehicle. P0740, 753, 758, and 785. So they assumed a short in that harness. After that was replaced, same issue except now it is 3rd gear all the time. They suggested an "electrical diagnosis", I guess for shorts or non-transmission, non-"mechanical" stuff (computer / sensor stuff), but I hate taking it somewhere else ($$) for what seems like more guess-work. Maybe slap in a salvage yard ECM (main computer) and see what happens? An associate at the local Chev dealer said maybe the ignition switch.
Tuesday, October 19th, 2010 AT 4:34 PM