Greetings all!

On my wife's 71 xj6, the alternator either charges correctly, or sometimes overcharges when NOT under any load.

It is stock, with a/c, and the Butec alternator with the external voltage regulator.

The dash battery gauge reads opposite of what is happening. When I hook up an external meter to the battery directly, it displays correctly, showing when it is overcharging, while the dash gauge shows discharge or low volts.

While the car is being driven, you can hear and see when there is a voltage change by engine sound of a load change, or dimming/brightening of the lights. As posted in another thread, the mysterious smell has been found to be battery sulfur.
While the car is idling with the external gauge hooked up, the voltage regulator's adjusting screw does seem to function while under a load of lights and a/c.
So......... I would assume the alternator is fine because it does charge, and this could be traced back to a faulty voltage regulator.
Thoughts? Would you replace the external regulator with a new replacement, or opt for the GM Delco one wire alternator?
Thanks for any and all help.

 

3 wire delco alt with pig tail and a length of wire should cost 50$ from a local big box auto parts store.

Get a 3 wire so it replaceable. 1 wire is a specialty its not commonly available. So a few years from now if you are on a road trip and you needs a repair it will be easier.



Repalce the 16ohm resitor with a lamp and this will be your alt warning lamp.

 

Agree.


Easiest path. But, you may need an adapter to replace the Jag unit with the Delco.


Johncars of the Dallas Worth, Texas area sells them. No affiliation, merely good past dealings.


Years ago, I suspected electrical oddities other than the expected on the Jag volt guage (?). Very slow on the pickup.


I made a patch cord to connect my VOM via the cigar lighter outlet. Now, I could read volts at rest, and rpm's and load conditions. Alternator passed. Battery flunked. A new one and all was well.


Carl

 

Thanks for the replies!

Couple of questions. What do you do with the wires from the external voltage regulator? And on the back of the alternator there is positive batt wire, a ground strap, and two other wires, they are?

The wiring diagram shows that a lot of them are the same or at least tie in together at some point.

 

Just finished the swap/conversion. I will post a "how-to" with pictures. I ended up using a GM Delco 1-wire alternator and it works flawlessly (so far).

 

As a decided non expert in electrickery, I understand that the difference in one wire alternators from the more common two wire units is excitation. The little wire excites.
The one wire excites it self by a bit of rev. Ok if idle revs are enough. Not so much if engine idles quite slow.


My LT1 idles at a steady 500 RPM. Enough for a one wire, I dunno. It's big 140 amp Delco is more than adequate for me.


Carl