I have an Amigo value shopper that is not wanting to charge. What do I check to find out what part of the charging system is bad.

SOURCE: Check charging system light...

you might have a bad battery, try disconnecting the negitive battery cable, then the positve, wait 2 minutes and hook positive back up then negitive.good luck

SOURCE: troubleshooting charging system problem

First need to know what type and make of car you have.
most likely not on the problem in the door being any relation to the charging system as this is a seperate system.
and as for the alternator putting out voltage, if you put a volt meter to the lug on the back it should read about 14 volts, however this is not set in stone. you will also have to have the proper amps comins out.
I would take the vehicle to someplace like autozone and have a check done on the battery and charging system as they do this for free. As long as both check then you most likely have a wiring problem from alternator to battery issue.

SOURCE: 2001 Lincoln LS electrical system SHUTDOWN

change the drive belt and have the voltage regulator in the back of the alternator checked out and also check for any draws on the car anywhere cause this can cause the alternator to over charge trying to keep the battery charged up

SOURCE: Check charging system

So you have a new alternator. I S IT CHARGING ? If the answer is yes , and the battery still dies, I would say there is a 12 volt drain in the electrical system. Hope this helps

SOURCE: charging system

Check/test all charging system components. Have battery tested; check cables for good connection and corrosion; check belt for looseness or cracks; even if you just bought a new alternator, it could still be bad. There are alot of shops and parts stores that will check your charging system for free.
If it's discharging when vehicle is just sitting, probably a bad ground or loose wire somewhere.