How do you test alt output?

[bustanutley]

Two things you can always try if you don't need a real answer. Pull the pos/neg with the truck running. If it dies, the alt isn't working. You don't need a battery for the truck to run. Also, the alt becomes a magnet when it is working. Stick a screwdriver to the back of it, where the post is that everything spins on. If your screwdriver sticks it's doing something. All this really tells you is if it isn't working. Anything else it might be working.

This will tell you straight up if your alternator is working, turn all accessories on before you pull the terminal that way you don’t' spike the system and kill the engine and you will still be pulling a good load off the alt.