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Hello fellow corvette owners, here is the problem I am having with my alternator, my 69 corvette seems to have an exterior regulator (original wiring) for the alternator even though others are saying 69s and later came with internal regulators, I just put a powermaster 100 amp external regulator alternator and it gets hot after a few minutes, not just warm, even with the engine off and cold, I thought it might be a bad alternator so I put another new one in and the same issue, does not sound normal. Could it be a bad regulator or a short wire somewhere? here is a photo of what I think is the regulator, is this the original ? Thank you for any help I can get.
That's not a regulator it is the horn relay.
All 69's came with internal regulator.
Sounds like you installed the wrong alternator.
https://willcoxcorvette.com/corvette-horn-relay-replacement-14981
My '70 came with an internal regulator alternator. Within a short time when new, the alternator failed. The internal regulator had failed, and there were no replacements available anywhere. A high failure rate had used up the supply of regulators.
The dealers were instructed to install an external regulator, which was done. Many months later the internal regulators became available and mine was converted back to internal regulator.
Perhaps your '69 was a victim of this as well and never got converted back.
Note... The original alternator was still used, however the internal regulator was removed and wires ran out the hole to an external regulator. GM had provided the wiring information required for the external regulator conversion. So it's likely you could convert back to an internal regulator alternator.
Last edited by Barry's70LT1; Jul 26, 2020 at 02:49 PM.
I guess my confusion arises from the fact that original wires on my car is set up for external regulator alternator, the car since I have owned for thirty years always had the external regulated alternator I don't remember ever having this issue before. Is it possible that some 69s were installed with external regulator alternators? Ok I noticed that the external regulator is missing, so if I want to convert to internal regulator what do I do with the black ground wire? It seems like Powermaster internal alternators do not have a place for the black ground wire.Thanks
Last edited by 69vette$; Jul 26, 2020 at 06:06 PM.
If you have an external regulator, where is it???
Below is a link to a 1968 regulator.
https://willcoxcorvette.com/corvette-voltage-regulator-replacement-63-68
How about posting pictures of what you think is an external regulator wire harness on your alternator?
What is the part number and manufacturer of the 100 amp alternator you installed?
Take a picture of your present alternator and/or give us the part number. Your 69 should be internally regulated. If you are going to get a better alternator then go to a CS-144...no need to half-@ss things with some "upgraded" 12si if you're upgrading the alternator.
Take the readings below to determine the status of your wiring to begin with......
Here are some pointers for that: Here is the guidance I used to find the adapter for my CS-144 (been installed since 2007)..... should work for a CS-130 from what I have researched. If nothing else you'll know how to measure resistance. (Additional info: I also had converted my 68 from an externally regulated 10dn(?) to an internally regulated 12si. I bought the 12si-to-CS adapter because when I did it CS-144s were still somewhat rare. Works out good though, I swapped in my old 12si one day when I thought I had messed up my CS-144 and it worked just fine.)
You can do the quick check below to see what adapter you need to convert from 12si to CS-144 ...then go to the local parts store and get the equivalent part. I went to NAPA, mine took Echlin part # ECH EC82 .... according to NAPA website that is part interchange number for 8078 in text below. (Per NAPA website: 8077 cross-references to Echlin part #ECH EC80 8078 cross-references to Echlin part #ECH EC82)
(****THAT WAS FOR MY VEHICLE ---YOU NEED TO DETERMINE YOURS****KEEP READING).
"If you are unsure which adapter to use, measure the resistance of the exciter line. Disconnect the positive battery cable and the alternator plug. Connect an ohm meter between the #1 terminal on the plug end of the alternator harness and the end of the positive battery cable. Turn the ignition key to the "on" position and read the ohmmeter. If resistance is less than 35 ohms, use adapter #8078. If it’s between 35-350 ohms, use #8077. If it’s more than 350 ohms, you have excessive resistance somewhere in that circuit which needs to be repaired, first."
...the above text is from idavette dot net (doesn't appear to work anymore).
that's the guidelines I used to wire mine in and it worked from the get-go.
I am posting a picture of the alternator wiring which I think is correct for internally regulated alternator for 69 vette, however a Corvette specialty shop that did repairs on my car looks like replaced my existing alternator with PowerMaster 17102 alternator which is an externally regulated alternator, even though I don't see an external regulator under the hood, he even switched my two wire plug to make it fit and now the alternator heats up when plugged in even with the engine off. First I thought maybe I was missing the external regulator until I found out that 69s don't have external regulator. Can someone confirm that the wiring you see is correct for internal regulator alternators? Thanks
I looked that thing up. That is an EXTERNALLY regulated gm alternator, with the original type plug that went to a 68, and it looks like it's boosted to 100-amp..... and it is NOT correct for an internally regulated 69. You need to get away from those clowns. I can't believe the pulled that crap on you.
You need to get the correct alternator and a wiring diagram. The plug for a 12si is readily available at a parts store. It ain't rocket surgery but I don't know what your capabilities are.
I converted my 68 to internally regulated and used to have a 94-amp 12si which worked fine until I added a/c, efi, efi fuel pump, and then I went to a 140-amp cs-144 so i could maintain voltage at idle.
If you don't have any excessive additional loads, then a 94-amp 12si should be more than adequate.....depending on how much wiring mods you want to do.
SO- what do you want to do?
I am posting a picture of the alternator wiring which I think is correct for internally regulated alternator for 69 vette, however a Corvette specialty shop that did repairs on my car looks like replaced my existing alternator with PowerMaster 17102 alternator which is an externally regulated alternator, even though I don't see an external regulator under the hood, he even switched my two wire plug to make it fit and now the alternator heats up when plugged in even with the engine off. First I thought maybe I was missing the external regulator until I found out that 69s don't have external regulator. Can someone confirm that the wiring you see is correct for internal regulator alternators? Thanks
Can you go back to the shop and ask why they did that to your charging system? It really makes no sense why a qualified Corvette shop would do that.
the alternator in the background is a correct internal reg alternator. how much extra did they charge for shiny polished case on the alternator? we don't smoke in our cars. everybody should get one of these...
I spoke with the mechanic he apologized for the mistake and offered to replace it with the correct alternator, his lame explanation was that and I quote " I installed whatever alternator the part department gave me" and this is their top corvette restoration guy mind you. Thanks to everyone for their help.
I spoke with the mechanic he apologized for the mistake and offered to replace it with the correct alternator, his lame explanation was that and I quote " I installed whatever alternator the part department gave me" and this is their top corvette restoration guy mind you. Thanks to everyone for their help.
If you cannot DIY w/ help here, take you car to an established local auto electric shop. They can spot the right or wrong alt from 6 feet.
Bird just retrofitted a CS130D to a customers 73; not hard at all.
Get away from that IDIOT. If he is too much of a moron to not recognize that modifying the wiring to make a supposedly "stock" replacement part fit is the WRONG thing to do, then you don't want him touching your car.
Originally Posted by 69vette$
I spoke with the mechanic he apologized for the mistake and offered to replace it with the correct alternator, his lame explanation was that and I quote " I installed whatever alternator the part department gave me" and this is their top corvette restoration guy mind you. Thanks to everyone for their help.
Last edited by carriljc; Jul 27, 2020 at 09:15 PM.
I spoke with the mechanic he apologized for the mistake and offered to replace it with the correct alternator, his lame explanation was that and I quote " I installed whatever alternator the part department gave me" and this is their top corvette restoration guy mind you. Thanks to everyone for their help.
I would request my money back plus the cost for the damage to the wiring harness/repairs. He could have burned down your car and maybe your garage, house and you with it. Kind of makes Bubba look good and he actually charged you to do it....
Last edited by CanadaGrant; Jul 28, 2020 at 10:34 PM.
69 alternator issues
