1970 e300...302....Somebody please help. Alternator light on. I replaced the alternator, voltage regulator, AND battery. Light is still on and not charging. Am I totally missing something? Thanks

 

Do you have a light or an amp gauge?
Do you have power coming from the Ignition switch to the alternator?

 

yes. its starting. just not charging.

 

Has it always started since this happened? If it wasn't charging eventually the battery will be dead. I would check the wire going from the positive battery cable to the alt. there should be a fuse or fusible link in that wire. I would also check for corrosion at the battery cables and wires.

 

Did you check with a multimeter to verify that it is charging / not charging ? The Factory guages are not that great.......

 

Okay. Here's what happened. I was at the lake for the weekend and everything was fine. Started it to drive home and the ALT light came on. I looked at the volt guage and it was on 12 but I took my chance and drove home anyway. Trip is about 50 miles. No problem and the guage stayed on 12 all the way. When I was about 5 miles or so from home, suddenly the ALT light went off and the volt guage went up to about 14, which I guess is where it should be. It was very rainy last weekend and the humidity was terrible. I figured everything was just so wet and when it dried out everything was fine. Didn't use the van all week and when I went to start it Friday, the ALT light was on again. So I figured it was the voltage regulator since it drove all the way home from the lake without dying. But the light stayed on. So I went and got an alternator, but nope, light still on. So now I'm thinkin battery, so I took the battery out of my truck and tried it and the light is still on. Is it possible I got a bad voltage regulator? I've read the new ones are kind of junky. Sorry post is so long, but I'm going crazy with this. And now I'm running out of daylight so I can't do anything more till tomorrow afternoon. Well thanks again for the help.

 

At this point I wouldn't trust the light and/or gauge without symptoms or testing with a voltmeter. Yes you can get a bad regulator or alt. May just be a wiring issue to the gauge.

I recently had issues with my coolant and oil pressure gauges turns out it was my starter causing erratic readings.

 

A good test would be to start the van & disconnect the battery completely. Will it keep running? If so, alt's good.

Based on what you said my first guess is the wiring from alt to battery, it matches your description prior to the new alt.

 

Bad information. Never do this.
The voltage can go as high as 100 Volts and take out the alternator, radio and other modules.

 

Please explain how this could happen since the battery is not a voltage regulator in any way.

 

OK. just got home with my new meter/tester. Now I dont know what to start checking. HELP

 

check voltage at battery with truck off vs on. Off should be 12 or so, on should be 14.5. If on voltage is less than 14 the alt's not working properly.

(you need at least 1500 RPM's to spin up the alt correctly)

 

OK. Just fired it up and the battery voltage came down a hair. From 12.66 to 12.46. I had it revving pretty good too. I took the Alternator to Autozone and had it checked. Its working fine. When I hooked the meter directly from battery to the big red terminal on the Alternator there is nothing.

 

take reading with Positive lead to the nut ( Big red wire) on back of alternator and a good ground ( also could be Negative Battery terminal) ...this reading is alternator output....This should be 13.8-14.5 volts.....

 

The battery is the filter capacitor for the charging system and also supplies the voltage (current) to the fields of the alternator. If the battery cable is pulled off while charging the spike in the electrical system can go as high as 100 Volts. The regulator can not work without the battery either.