Steps to check if alternator is dead:
1. Start your engine (get a jump from a good running vehicle if necessary).



2. With the engine running, disconnect the battery. If the engine dies-your alternator is dead, if it continues to run, your battery is dead. The reason for this is that the battery is used only to start a vehicle and occassionally to assist in accessories (headlights, stereo, AC, etc...) during idle or traffic stop. The alternator keeps the fuel injectors and ignition system (onboard computer, etc...) going once the vehicle has started and begins to recharge the battery from the energy used to start the vehicle.



3. So if your engine still runs after disconnecting the battery, the alternator is doing its job correctly. If it dies, then the battery was the only thing supplying the ignition system and everything else.



4. Please know that 90% of alternators die due to a failing battery.



5. So if it proves to be the alternator, you may want to replace the battery as well, unless you're sure it wasn't the battery due to age, etc...



Rep it up Thanks

 

2. With the engine running, disconnect the battery.
http://www.troubleshooters.com/dont_...ct_battery.htm
better safe than sorry

 

lols thanks

 

Whoa!!!!!

So whats the consensus? Disconnect the battery when the engine is running or not? Is there another way to test the battery and/or alternator without the method stated in OP?