1979 Vette charging problem
 

Still a newbie here. I have received excellent help on this site. My problem this time is everytime I have to start my car I have to jump it. The battery and alternator are new so I am not sure where to start looking. After I jump it the volt meter stays around 8and I have to rev it pretty hard 2 or 3 times before it jumps up to the 12 volt range. Anyone have any ideas.

Thanks

RE: 1979 Vette charging problem
 

Check all battery, alternator, &connections and make sure they're clean & tite. Then if that doesn't fix it, take the car to a auto parts place that tests batteries and alternators for free. I have put on a new bad alternator and also had a battery fail in one month.

RE: 1979 Vette charging problem
 

check spark plugs and distributer, however i'm not a genius but know my share ofstuff

RE: 1979 Vette charging problem
 

Sounds like the new alternator is not responding at the lower engine speed, you need a clean new belt at the proper tension, good electrical connections and a battery that's in shape to accept a charge. temporarily hook a known good battery to the vette and disconnect the the other one, start the engine and let it stay on fast idle, connect a DC volt meter to the donor battery, you should see 13.2-14.8 volts, if it's lower than 13.2 the alternater and/or internal regulator is at fault.

RE: 1979 Vette charging problem
 

Hello again Riley6Riley, You can never assume that just because a battery or alternator is new that is good, do like the other members suggested and you'll find that one or the other is no good. Good luck, PG

RE: 1979 Vette charging problem
 

I am on my way to the auto parts store tomorrow and have them test it. I will let you know. Thanks again.

RE: 1979 Vette charging problem
 

Well I took it to Advanced Auto Parts and they gave me a new battery (the other new one was shot, only a month old) and I am still having the same problem. The voltage regulator and diodes test ok and I am going to try to get the alternator tested tomorrow. It is only putting out about 1-2 amps so something is going batty.

RE: 1979 Vette charging problem
 

HI,I thought the voltage regulator and diodes were inside the alternator?
Tell me again what year is you vette, thanks, PG

RE: 1979 Vette charging problem
 

My Vette is a 1979 L-48. When they hooked it up to the "test equipment" it said that the diodes and regulator were good. I am going to take it to an alternator place this week and have them test it. You are right, everything is internal on this alternator (stock).

RE: 1979 Vette charging problem
 

When we looked up the alternator to make sure that it was the right one (which it was) this was on the write up:
INSTALLATION ALERT! A blown fuse or bulb in the warning lamp circuit may cause a "no charge" condition.

Is this just a fuse in the fuse panel they are talking about? Do you what this means?

RE: 1979 Vette charging problem
 

Good morning riley, I'l try to give you a little help based on the schematic I have for my '78. First off, do you know the history of the car-was it charging correctly at any time since you've owned it? What repairs were made that may be at the root of your electrical problem? The alternator should have a single red 12 gage wire with a ring terminal that mounts under the insulated nut on the back, also you'll have a two-wire connector that plugs in at the top rear- this should have a small red and small brown wire. The two red wires are tied together in the harness and both should show battery voltage at all times, the brown wire goes to the GEN light on the gage cluster- this light should come on with the engine turned off and the igniton key turned to the RUN or ON position, to my knowledge there is no fuse in this circuit. If all of the wiring is intact and connected to the proper terminals the system should begin charging as soon as the engine is running, use a volt meter hooked up at the large red wire and a good ground- you should see 9-12.5 volts with the engine off and 13.2-14.8 with the engine running and a fully charged battery. Let me know what you find.

RE: 1979 Vette charging problem
 

Before I bought it, the lady I bought it from put a new alternator in, distributer, wires and she was getting ready to put in a new battery when I bought it. So there probably was a problem. I put in another new battery yesterday and the voltages checked out fine on the battery, but it was slowly draining the battery and wasn't producing hardly any current. I will check the voltages on the alt and letyou know.
Thanks

RE: 1979 Vette charging problem
 

Sounds like more issues than just alternator and/or battery.

RE: 1979 Vette charging problem
 

Like78buckshot says,it's starting to sound like it could be other issues. But that's OK, with everyones help you have it fixed in no time.
Once you've done the above tests and checks theres a good chance that the problem will be fixed. But if your battery goes dead again then we'll have to search for a "short". Do you have a light in the storage compartment behind the seats? Check to make sure that it goes out. Then see if the Door Ajar and interior light switches (on the door frame) are working.
If that is not the problem then disconnect the pos battery cable and put one lead from your volt meter to it and the other volt meter lead to the battery. You hope to read zero volts, if not pull the radio fuse, if you now get zero volts check the radio wires.
If your volt meter still shows a draw then pull each fuse one at a time untill you get zero. That will tell you what "System" the problem is in and you can then check that systems wires and connections. Hope this helps. PG>

RE: 1979 Vette charging problem
 

I think it is becoming a short problem too. I measured the battery and was reading 12.41 volts and then measured off the alternator and was reading 12.4. I checked back about 5 minutes later and it was reading 12.38 so it is not charging up. I left the battery hooked up and checked it about 3 hours later and it was reading 12 volts so there is a draw somewhere. I am still stationed up here in Rhode island and I am going back down to Virginia Beach this weekend and will check the short problem and start pulling fuses.

Thanks for all the help so far.

RE: 1979 Vette charging problem
 

PG,
I disconnected the positive wire like you said and I measured 12.44 volts from the positive battery terminal to the positive battery cable so it looks like I need to start pulling fuses.

Well, I took it to the alternator place and said the alternator is fine but there is a short on the brown wire that is coming off the back of the alternator. He said that it could be cracked or touching something. I followed it back to the firewall and haven't got much farther than that. Does anyone know where this wire goes/comes out inside the car? Does it go right to the GEN light? Not sure where to go from here.
Still checking

RE: 1979 Vette charging problem
 

I pulled all the fuzes and I am still reading 12.44 volts from the red battery cable (disconnected) to the positive terminal? I measured from the disconnected red battery cable to the negative terminal and I am still reading zero volts (I assume this is correct) so I am not sure what to do now.

RE: 1979 Vette charging problem
 

To check the altenator without much trouble...start the engine and with it at idle remove the ground wire of the bat...if the engine cuts of the alt is your problem...

RE: 1979 Vette charging problem
 

looking at the repair manual i believe that brown wire does go to the generator warning light. i had a similar draw on my 79 itwouldkill the battery in a day.not sure what fixed it cause so much electrical clean up was done when i bought the car but i believe it was the starter wires. worth checking them out.

RE: 1979 Vette charging problem
 

Hi again, sorry those tests have not located the problem so lets continue, lets leave both battery wires connected and pull one fuse at a time. If you have no draw as you check across each removed fuse then the amp meter may be the problem, PG.

RE: 1979 Vette charging problem
 

There is one other place to look, the ground wire from the wiper switch, runs down to the bell housing, it has a large connector at the end and it should be connected to a bolt on the bellhousing, sometimes if is mistakenly connected to the starter terninal & that to will bleed of your battery voltage. Take a look to make sure that is connected correctly PG.

RE: 1979 Vette charging problem
 

I did find that the draw was coming from the gree/brown wire coming from the back of the alternator (one of the wires going to the diodes). I traced it back and could not find anything wrong with it. I ran another wire that was hot when the ignition key was on and jumpered it to the alternator and everthing runs great now. I guess it just needed 12 volts....

Thanks again for the help. I really learned alot chasing the gremlins....little nasty &^%$