"Wrong" is not something I can analyze. There is one small wire that bolts to the small terminal on the starter. It is impossible to put that one in the wrong place. The larger battery cable goes to the large terminal. You are not likely to get that one wrong either.
Where mistakes can be made is GM likes to use that larger terminal as a convenient tie point for other circuits. That is done simply to reduce the amount of wire needed for multiple circuits that run back to the battery. Sometimes those wire are overlooked and are not hooked up. One may feed the entire interior of the car, and one may come from the generator. If the first one is left off, everything inside the car, including the ignition switch, will be dead. If the second one is overlooked, the battery will run down in about a half hour of driving, then the engine will stall.
To verify the generator wire was left off, measure the battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it stays around 12.6 volts or less, measure the voltage on the large output terminal on the back of the generator. If you find a higher voltage there than at the battery, that output wire is not making it back to the battery, and that indeed could be that forgotten wire by the starter.
Wednesday, May 10th, 2017 AT 10:45 PM