The other day Im driving and the gauge lights are dimming, then the ABS INOP light comes on, then right before I get to my house the car starts running real rough. I barely make it in the driveway, shut off the car, then restart--batterys dead. 20 mins later it starts up but will only run for a little bit. A couple days ago I removed the alternator to do some exhaust work and I suspect I screwed it up somehow. WHat could I have done wrong? Its 4 bolts, that clip thing, and the wire and screw in the boot. THe belt is going fine and on correctly. How can I tell if I need to replace the alternator or a battery? Thanks.

 

You must test the battery for load carrying capability first. That means charge and load test it. Take it somewhere for that. While it's out, check the grounds for the engine and the frame. Once a good battery is in the car, test the voltage across the battery while it's running. It should be close to 14 volts.