Tell your brother that disconnecting the battery cable is very old school. That is the way grandpa used to check the alternator but if you try that today it could ruin your electronics. In the old days cars did not have sophisticated electronics and it was a good test. Don't know why it shut down. maybe because the alternator is bad, or maybe because lack of electricity to the cars on board computer, or worst case because you short out some electronics.

Check the alternator with a volt meter.

What do you mean by "kicking out"? Do you mean that it is dropping off, or that it has a constant 14.4V output and plenty of current?

The alternator should provide all of the voltage and current that the vehicle needs to continue to run after the battery is disconnected. If your car dies, then there is a loss of voltage somewhere. All it takes is less than a half second of voltage loss to drop out your ignition relay. Maybe the regulator is not operating fully, but well enough to keep the battery charged and the system running with the battery in place as a buffer.

burt is correct, put a volt meter on it, and it should read 13.8 to 14.4 volts to show it is charging, and use it is old school and can cause damage to computer and other things if you don't have a complete circuit. also, before I knew better when they first started coming out with the new systems, I use to use that trick, and one day I had the lights on and when I pulled the battery loose, it blew every bulb, tail and head lights. so don't do it with the newer cars.

Duckman's on it. Alternator has to be "kicking out" around 14 1/2 volts, if your reading around 12V, that's just battery voltage and alternator is shot. BTW, while the battery cable test is fine for a '66 Chevelle, computerized cars, not so much. Use a voltmeter.

Had the same problem. Try replacing the wire that goes from the back of your alternator to your battery cable. They don't sell them so get you some 10 gauge wire and some connector ends and try that. It fixed my problem on my 1994 Chevy Silverado Z71. Cost around $10 depending on the length of the roll of wire you buy. Go to AutoZone. They'll show you exactly what you need

my car run and when i get the alternator checked it shows that it is kicking out but when you take the positive cable off the car shuts off.... my brother did it with his car and it kept running.... Please help