Battery light stays on

[Bulldog]

I have a '81 4 barrell. I replaced my battery with a new one and the battery light stays on when the ignition is turned off. Also after replacing the battery now the car won't start. It cranks but it won't start. Can anyone tell me why?

 

[78 Shark]

check for voltage

Hello Bulldog,
Check to see if you are getting 12 volts to the distributer, not the tach wire but the red one when the key is turned on. If there is voltage then the problem could be the module in the distrubtor. Hope this helps.
78 Shark

 

[Bulldog]

Thanks for the help 78 Shark , I had 11.34 volts but I tried something ,I took a wire and ran it from the positive terminal to the red wire and by passed everything and it fired right up no problem,hooked everything back up and it seams to fire up with no problem,but I'm still having a problem with a battery light staying on when the car is shutoff.I was told 2 things that it could be, 1 maybe a bad ground from the battery to a juction box some where on the frame.2 (I think its called a diode) alternator. When I disconnected the wire from the alternator my battery light did go off,so I'm going to go and get that checked tomorrow,does any of that sound like it maybe the problem?

 

[Curtis]

i would put my money on a blown diode trio in the alternator.. that will prevent the alternator from charging and may drain your battery. Since it cranks over and starts with the jumper , I doubt you have a bad ground issue.

 

[Bulldog]

Thanks Curtis,
I'll take it up and get tested today,Thanks again.

 

[Bulldog]

When going to get a new alternator they asked what amps the old alternator is,I would guess its still the original aternator and I'm not 100% sure.I do have some stuff added like a security system and a after market stereo,stock a/c unit still in there.Does all these make a difference in what amp size i need?And what is the standard or stock amps?

 

[JohnZ]

When going to get a new alternator they asked what amps the old alternator is,I would guess its still the original aternator and I'm not 100% sure.I do have some stuff added like a security system and a after market stereo,stock a/c unit still in there.Does all these make a difference in what amp size i need?And what is the standard or stock amps?

The standard alternator was 63 amps, and 70 amps with a rear window defogger.

 

[Bulldog]

IT WAS THE ALTERNATOR THE WHOLE TIME,BATTERY LIGHT IS GONE NOW AND RUNS LIKE A CHAMP!!!

 

[6880 Mike]

i would put my money on a blown diode trio in the alternator...

I agree. Alternator is dying.

 

[Mr. Chuck]

I had similar problem on my 81, went to local parts shop, purchased a new diode trio (~$8), replaced same in alternator and no more light problem, if you have experience / knowledge you can saved the cost of a replacement alternator.