my firebird has been down for 8months finally got it going again. changed the l03 out for a l05 and did all the mods. now when i start the engine the volt guage says about 10 v, and when radio would come on it would drain in no time so i figured time for an alternator. battery was brand new. got a lifetime warranty one and put it back on still showing 10 v but dont drain near as quickly as it did before.but at about 25 minute period and its dead.now only thing that i might have done wrong that i think of is by accident forgot to hook alternator 3wire plug and the little wire with the screw on nut,at the intial start of the new alternator and my brother shut enginge off and these were plugged in and started it back up and still the same. anyone see what ive done here. i also just taken the alternator backto get another one )which i got) but their tester was bad.put the new one on and still the same.lights work okay turn signals hazard.and thier not that dim like they should be. please help if you can.

 

Check your battery cables!! Many times people let the negative cable go and only worried about posative. The negative is just as important. The other thing to check, this just happened on my LO5 89 truck motor, is on the posative cable where it connect to the battery there is a second wire that is about a 6 AWG wire that connects to the battery terminal. This wire lost connection inside the terminal boot and gave me the same symptoms that you describe. Volt gauge was below 10v before the added resistance killed the alternator. The great thing about this wire breaking down was that the alternator was charging at 14v but only 10 was going into the cab of the truck. When the wire died i had no interior electrical but under the hood still worked. Hope this helps ya out.

 

I forgot to hook the cable from the alternator to the little hot terminal by the battery and my car wasnt charging like you said. I felt pretty stupid after I spent a day trying to track it all down.

 

ok i followed the advice and i think ive got some starters wires a little mixed up too. i went out and popped the hood ran a wire from the back of alt to the pos post and the car started. adn no there wasnt any one in the car and no clutch pushed in either.im going to go back to the starter and figure that one out. probably got that one wire mixed up. thanks for the info guys.