knighthawk

70 Cutlass, gen lite will not go out when I turn the key off. And drains the battery over nite . .....new Alt and Reg

droldsmorland

External regulator or alternator fault. But before you replace anything lets cover the basics...What is the battery surface charge when its not been drained? Does the battery pass a load test? Does the car charge properly off the alternator, 13.8 to 14.2 vdc at idle spec? Have you inspected and cleaned all grounds including the regulator to firewall interface? Pull the regulator lid and see if the points are stuck when the problem occurs. If you turn the key on/off a few times(without starting the engine, but do bump the starter) will it go out? My 68 did this. When cycling the key. I could actually hear the regulator release with a twang noise. I replaced the regulator(after testing it and the alternator) with a solid state reg problem gone.
Not saying this IS your problem. Answer these basic trouble shooting questions from above and we'll be able to zero in better and dig deeper into Alternator/regulator verification testing.

Rustbucket2

I had this happen once, I had a bad diode in my alternator , was told there are three, the others will follow soon, so I replaced my alternator. But do follow the steps droldsmorland has, could save you money.

knighthawk

the car belongs to a friend, says a new Alt and Reg didn't help. So, I just checked it, bat voltage was 12 , charging at idle 14, . Here's what is ; key off- alt lite brite, key on Alt and Hot lite dim, running, Alt stays on dim . .....Off, there is always a good spark when I touch the battery post. I couldn't check the points as you suggested, no helper today.
spark is when I touch the red wire from reg to relay post

droldsmorland

"Dim or illuminated Gen light:
The GEN light does not ground in the instrument panel. The bulb is supplied with +12v with the key in the RUN position. The other side of the bulb is connected to the #1 terminal on the alternator (assuming a three wire, internal regulator alt, like the SI-family). In the regulator, the #1 terminal is grounded when the alt output is low and should be full alt voltage when the alt is charging. By having the same voltage on both sides of the bulb, it does not illuminate. If voltage on one side (and it could be either side) is low, current flows through the filament and the bulb starts to glow. The greater the voltage differential, the brighter the bulb. If the bulb is glowing dimly, you have a voltage drop on one side of the bulb. Start by checking output voltage at the #1 terminal on the alternator - it should be 13.8V or so. If you can get to the IP connector or the two terminals of the bulb socket, check the voltage of each of those to ground with the engine running. They should be the same. If one is lower, find the voltage drop in that wire. It will likely be a dirty connector terminal someplace".

"The only difference is yours is an external regulator and the light is fed from the regulator connector on the firewall terminal #4, I think it's a brown wire. The brown wire goes through the bulkhead connector and then directly to the light. On the other side is a pink wire that also feeds power to your fuel gauge, temp light, parking brake light, and oil pressure light. So depending on which side of the light is low (brown or pink wire to ground) that will be the direction you need to go".

credit due: Joe Padavano or Harvey White? Likely Joe.

knighthawk

thanks, I will have to wait til this evening to check any more , as I am supposed to be working on my house remodel ....... thanks

Octania

While the light is illuminated and it should not be... disconnect things one at a time until the light behaves, indicating the source of the problem.

ALT 2-wire
Fat red alt wire
regulator 4-wire...

PS "new" is not equal to "works right". Do not make that assumption. Some folks use "new" for "different" also.

70CutO

hello everyone, I'm the owner of the car. knighthawk is a good friend of mine and helps me when I'm in need! The problem on my 1970 cutlass s , started when i replaced the pig plug on the back of my alternator. Sadly they were backwards... when installed... ruined my battery, alternator and external regular (mounted on firewall). So I fixed the wires in the pig plug back where they are supposed to be. Brand new battery, alternator, and external regulator. Droldsmorland: Where did you purchase your solid state external regulator?


Thanks for the advice everyone!

Fun71

Solid state regulators are available from most auto parts stores as a replacement for the original, old style mechanical regulators.

MDchanic

Are you saying that any of the wires overheated when the terminals were reversed?

If so, then you could have wires crossed inside one of the harnesses.

- Eric

droldsmorland

Here ya go. Make sure to save the stamped cover off yours and install it onto the new one, if the OEM look is desired. If you happen to have the original stamped designed cap dont toss it. If you dont want it sell it to some who does. Could pay for the new reg.

http://www.ebay.com/bhp/external-voltage-regulator

http://store.alternatorparts.com/10d...egulators.aspx