tbristol

I have googled and searched this site. I can not tell if the Previous owner of my 1970 cutlass convertible has switched to an internally regulated Alternator or not?? so attached is a couple of pictures. Hopefully enough to identify. I believe the regulator either internal or external is going bad. The volts read all over the place. Over 16 to as low as 12. I need to know if new alternator or just an external regulator. I couldn't get it to act up when testing but it read 14.2 volts coming out of the alternator on my test.

don71

That type of electrical connector tells me there is an internal regulator in that alternator. Somebody could have changed the connector though.

Is there still an external voltage regulator on your firewall? Its about 3''X 3''X 2''deep and four wires coming out of it. Brown,blue,red and white in color.

tbristol

Yes the external regulator is still there with wires running to it. This cars wiring it all hacked up. So because it is there. I can't tell you if it is still connected or not.

joe_padavano

Well, you kinda need to figure this out if you want to get a useful answer. The conversion to an SI-family alternator is easy, yet many people screw it up. Just be sure the wiring matches this diagram:

tbristol

for simplicity sake ... I have looked at that diagram 100 times in the past. So, can I assume. jumper the wire is the same as twisting the two ends together? I wouldnt do it like that, but is that what the diagram is saying? example twist the ends of the Blue and Brown wire together. Is the same as jumpering?

oldcutlass

Yes its the same.

joe_padavano

Yes, yes, and yes. There is nothing magic about jumpering vs. simply connecting the wires. Some people don't want to hack their original harness, thus the jumper. The electrons don't care, so long as there is a continuous copper path. You can remove those wires completely and run new ones - it doesn't matter so long as the end points are connected the same. Bottom line is that terminal #1 (the field wire) from the alternator plug needs to run to the GEN light on the dash. Terminal #2 (the sense wire) needs to run to the stud on the horn relay. The large red wire also needs to run from the threaded post on the alternator to the horn relay.

MDchanic

The alternator in the picture is an internally-regulated alternator, but, as Joe says, you need to be sure that Bozo the Mechanic didn't connect the internally-regulated alternator to the external regulator.

- Eric

joe_padavano

We've seen that here too many times, unfortunately.

tbristol

what would happen if this was the case?? I have had the car for almost 2 years and a motor shop has even had the motor out and the voltage has always read the same on my cheapo rally gauges inside. Just today I noticed the voltage was pegged at 16 then it would drop to 12 and so on. So if the external was hooked up to the internal alternator. wouldn't I have had problems before now? Can I jumper the wires as a test to see if everything runs fine?

don71

If I were in your shoes...I would check wire connections first.

Its worked for two years so maybe its right.

Clean the connections, scotch brite etc. Specifically the connection at the horn relay, and the others. At that point I would record the voltage again. Go from there.

If I (me) still had problems I would take the alternator off and replace the voltage regulator inside. Which means taking the alternator apart. Not everyone wants to do that, depending on mechanical aptitudes and dealing with the brushes etc.

Easy way out..go get another alternator.

MDchanic

Which, of course, is information you didn't give us at the beginning.

It sounds like it's connected properly, but there is a problem, probably with the internal regulator, which, as noted, is cheap and easily replaced.



+1.


No problem dealing with the brushes - there's a hole in the case that you stick a small drill bit or rigid paper clip through to hold the brushes in, then slip the halves together, then pull out the keeper you used, and the brushes drop into place.

- Eric

tbristol

just put 50 or so miles on the car, stop and go traffic voltage stayed at 14. So, I guess It was just one of those Gremlins that I will lose sleep over and never know what really happened. I'm definitely going to investigate this internal and external regulators on this car see what I can come up with. Thanks everyone..

oldcutlass

If its putting out 14.2 it is working correctly, if it jumps to 16v it needs an internal regulator. As the others have stated the wiring is easy enough to check.