nismorgan
+1y
while the engine is on, the alternator supplies everything therefore when you unhook the negative terminal, the car should still be running, if it shuts off this could mean that the alternator is bad, although this is not always the case, some cars, (not sure if our trucks do or not) require the use of a battery during engine operation simply to regulate the flow of current throughout the car. If the car does use this system, then removing the battery will cause a break in the circuit possibly stalling out the car. But...an easier way to test your alternator is to do an output test, get out your handy volt meter and probe the terminals while the engine is running, if its anywhere around 14.5 or so, then your alternator is working, if its at 12.6 and dropping...alternator aint workin. now you said that there was arking...what was arking?