My GM or Ford Alternator Does Not Work, What Now?

Troubleshooting Your GM or Ford Alternator

There are several things you can do to get to the bottom of a non-working alternator The first thing you should look to is the ignition wire that activates the alternator. Both Ford and GM, as well as most Import vehicles, us some sort of ignition wire. This ignition wire is fused so to check for a blown fuse turn the ignition on and check the ignition wire to the alternator. It should have power when the key is on an no power with it off.

Check battery: You must have a good battery with good connections for an alternator to work properly.
Check belt: Your belt must be in good condition and properly tensioned.
Battery Cable: The cable between the alternator and battery must be properly matched for the amperage alternator. If you are running a higher output alternator you must have a larger cable. We have found the even the factory cables are not large enough for standard output alternators. You should also consider running a separate ground cable from the alternator to the battery for better efficiency.