You can get a device from Harbor Tools that you plug into any cigarette type socket. It will test in general terms how your alternator is working. Just do a search on the internet for Harbor Tools and search their site for 12 volt Battery Alternator Tester Item 92571. You can probably find like devices in other stores, but I have used this simple and cheap tool to point me to these types of problems and then go from there. This little tool I am quite sure is less than $10 and could save you a trip to the dealer. Just keep it in your tool box. I have other sophisticated devices to go from there, but most of the time this device is correct.
