Definitely not. If the positive battery cable became grounded, the only thing that was shorted was the battery. Those can easily pass well over 250 amps to run the starter motor. A dead short will eventually melt the cables, including the negative cable, because the same current is flowing through both of them. Shorts to the rusty manifold are very inefficient electrical conductors, so it's unlikely you could get enough current to flow to do real damage to the cables.
What I would look for first, instead, is something that happened after the short occurred. GM likes to use the larger terminal on the starter as a convenient tie point. That is where the positive battery cable is attached too, and often one of the additional smaller wires gets overlooked. Also, depending on which part of which wire became grounded, there could have been some voltage spikes developed, and those can cause nuisance fuses to blow. Do not overlook checking the fuses under the hood and inside the vehicle.
There are also some vehicles where the large output terminal on the back of the generator is used as a convenient tie point for other circuits. There is a positive wire that goes straight from the output terminal to the battery. If that is the wire that became grounded, and the wire burned open, anything that branches off at the generator will be dead. That is real easy to test. Use a test light, or a voltmeter, to measure the voltage on the generator's output terminal. You must find full battery voltage there all the time.
Monday, November 21st, 2016 AT 6:28 PM