Hello all,

Since january I am the lucky owner of a quite nice 1968 327ci coupe Corvette.

As I just finished a quite long trip with it late april (about 1000 miles in 4 days), I noticed that the battery charge failed

I tried to trouble shoot it but I am quite lost. The alternator seems to act as a dynamo as it doesn't regulate the power.

The regulator installed on the car by former owner isn't a Delco stock one and I can't figure out how it is wired.

Here are the tests I made so far :
- Hooking off everything on the alternator, it outputs ~16.3V when motor is running
- About the regulator, on the picture, all the wires are black because it has been painted but on the front are wired +12V BAT :
- a wire to the battery positive
- a wire to the alternator positive but it seems to have some resistance around 150 ohms
- 2 other wires that leads I don't know where. Seems that it is a way to gain +12V BAT ...
- None of the 3 other wires is hooked to the +12V ACC as I donc gain 12V on it with the key in accessory position. They aren't ground wires either ...

If I disconnect all the wires of the regulator, the amp gauge falls to -20A whereas it is at 0 when connected. Note that if I use the power windows motor running, il goes by -5A. So it seems to work.

Does anyone recognize the type of regulator ? What other tests should I do to troubleshoot ?

I join 2 pictures of my setup.

If I am correct, on the regulator, I shoud find :
- one wire to +12V BATT (I found it)
- one wire to power switch (+12V ACC)
- one wire to voltage output of the alternator

That should be all as the alternator is connected on a "one wire" mode ...

If anyone can help to understand what is done on my corvette, that would be great !

Thank-you and excuse my poor english as I am French

 

That is not the regulator, that is the horn relay and key warning buzzer. The regulator will have a 4 wire flat connector and should be mounted to the right of the relay on the flat panel of the inner fender.

Also there should be a 2 wire connector attached to the 2 terminals on the right center of the alternator. The 2 wire connector senses voltage and activates the field to have the alternator charge the battery.

Do you have a wiring diagram for your 68? It would help you figure out what's there or missing.

 

The stock location of the 68 voltage regulator is on the fender skirt just opposite the alternator.

 

First of all, thank-you for your fast reply. And for the quality of the answer too ....

I posted about this on 2 french forum 4 days ago and still nobody pointed out that this wasn't the regulator but the horn relay !

For now, I do own the Assembly Instruction Manual and the Repair and Tune-up guide for the 1968 Corvette. I am looking for a digital copy of the color wiring as it costs as much to send to France than the product price itself ... The thing is that neither classiccarwiring nor DocRebuild sell digital copies of wiring diagrams. So I am stuck with those in black and white in my digital version of the AIM ...

I will try to check out at the real regulator this week and post a picture of it to this post in order to be sure that this time I do check the right component !!!

Thank-you again for your answers :-)

 

Thats a internal regulated alternator and youre external regulator is missing(I see the unused stud in the pic with the horn relay). Its very easy to convert that alternator to 1 wire operation, simply run a small length or wire from the power terminal on the alternator to the sense terminal on the alternator.

 

So I haven't the external regulator ... That explains that I was confused and thought that the horn relay was that regulator !

How can I be sure that this alternator is regulated (from the pictures, it should be a Delco 12SI) ?

Also, doing my research, I saw a site where it is stated that I should remove the internal 40 ohms resistor when building a self exiting alternator. Is it mandatory ?

Here is the source of this info ...

 

Looks like a 12si to me and that means its internally regulated. I've never heard of having to remove the resistor before so really cant comment on that. Id just jump power from the bat terminal to the #2 terminal and see if is starts charging(may have to give it a little rpm for it to "kick on").

 

Thank-you dugsgms74 for the info. I will try this and see if it changes anything :-)