My son has a 01 Honda Civic. We've replaced the alternator and battery so they are good. We've had them tested to be sure. Anyways it'll be running fine then all of a sudden as he's driving the lights go dim the dash lights come on and it dies on him. If we hook it up to a jump box it starts but dies as soon as we take it off. His battery will be completely drained. Does anyone know what this could be? We've been told multiple things from the computer to a sensor to a parasitic draw.

 

Check wirefrom b post to underhood fusebox for continuity
disconnect wire from b post and underhood fuse box and check with ohm meter for short to ground. Touch on end of wire and to body ground. Wire has to be isolated first.
Check connector voltage at alternator for batter voltage at IG terminal. With key on
Check voltage on L terminal
Check under dash fuse #24 to alternator
Check terminal cleanliness of underhood cable from b post AñD remove fuses and clean terminals.

 

1. Quote:

   Originally Posted by Fineedge

   Check wirefrom b post to underhood fusebox for continuity

Thanks for the advice. We'll try out your recommendations and let you know how it goes.

 

Sounds like a bad ground. There should be one ground going from battery to engine, one ground going from engine to chassis, and there may be a third. Just make sure the connections are clean, I find vinegar is great to remove corrosion, and 400 grit sandpaper or a wire brush. Keep us posted, should be a simple fix if the alternator and batter check out. I assume your alternator is pushing out at least 14.3V while running.

Cant be a parasitic drain (not saying you dont have one, but it's not your issue.), because once it's running the alternator should be able to charge the system enough to where that wouldn't be the issue. For some reason your alternator is not charging the battery. And if there is an alternator fuse definitely check that, but my money is on engine ground since that's what grounds the alternator.

Have you checked for continuity from the alternator positive to the hot lead on the battery?