I posted this on the electric board, can't seem to get this fixed. I changed out the alternator. Started and ran the day fine, readings were good. Next day, car is dead, no lights, no horn, nothing. Since then I have re-grounded the alt bracket, the neg battery cable to the alt bracket and body; pulled the battery to check and charge (the shop said batt had 560 cranking power and was only a little low). I have used a light tester, clip on ground probe on positive terminal, and get a "good" light. What have I done? Any suggestions for tests? What equipment do I need to buy to test?

. The tools for the job are a digital multimeter, wiring diagram, and a load of patience. First, why the alternator swap? I would check to see what the charging voltage is at 2500 rpms. Should be roughly 13.8-14.8 volts at speed. Any lower or higher and you have a charging problem. If good, use your mulimeter function with AMPS and check for a draw. First disconnect the neg. batt cable. Then hook one lead of the meter to the cable end and the other to the batt. Unless you have a stereo system with other components installed, the draw should be .020 amps or 20 milliamps roughly.

Check the fusible link in the line from your positive cable to the junction block on the core support.

My cable does not have a wire from it to the radiator.

does sound odd, if you pulled the bat. had it load tested ext. and its good we can rule out the alt. has a dead short in it. it would have pulled down the bat. could be a ground prob. or a major wiring harness got disconected, I'd trace the wiring, from the bat. find out where my 12 volt supply ends, if voltage is good you lost a groung.

What year model? Most years have a wire running from the positive battery post to a junction block. The junction block is located on the core support behind the battery. That wire supplies power to your fuse box and ignition switch. It has a fusible link and if the link goes bad or the wire gets broken it will cause the conditions you describe.

Did you make any sparks while replacing the alternator ?

On your 76 El Camino, 350, I think the fusible link is fist couple of inches of the wire that's on the Starter terminal post along with the positive battery cable.

Do you have a probe test light?
If so you can probe the wire at 2" , 3" , 4" from the starter.

Originally posted by Dean:
Did you make any sparks while replacing the alternator ?

On your 76 El Camino, 350, I think the fusible link is fist couple of inches of the wire that's on the Starter terminal post along with the positive battery cable.

Do you have a probe test light?
If so you can probe the wire at 2" , 3" , 4" from the starter. Or measure the large lead on the back of the alternator with the key off, which is what I suggested a couple of times. Yes Dean, starting in 72 the main fusible link moved down next to the starter, runs up the firewall, and out to the alternator. Back of the alternator is the first and an easy place to check the link. One sure way to pop the main fusible link is to change the alternator without disconnecting the battery.

I hadn't seen your post in electrical when I answered here, but did you ever find the source?

Listen to Dean and John they are steering you in the right direction.

Hey, thanks for all the help. With the suggestions provided, I went and bought a Meter (told my wife I was just following directions)and tested at the back of the alternator. I was only getting 2 volts, 12 at the battery. Dropped the starter (sounds easier than it is) and found what I thought was the problem. The positive cable to the starter was worn, and may have been touching something. As soon as I lowered the starter (supported) I checked voltage again, and had a good reading at the alternator. I replaced the positive cable and installed the starter ; didn't work, click or anything. Pulled the starter, tested it by jumping it, nothing. So I replaced the solenoid, reinstalled the starter. I could hear the solenoid click, but starter did nothing, dropped the starter, replaced the starter. Started right up, and worked all day yesterday. I will start it tonight to make sure all is well. I am not exactly sure what the root cause was, but I hope that I fixed the problem.

Thanks for all the help and advise.

I would still blame the main fusible link if it acts up again. It's right above the starter in the sponge like area in the small wire that attaches to the solenoid big post. It may have been moved when you had the starter hanging. Car acts up again, measure the alternator cable for 12 volts with the key off.