Firstgens.com

Hey guys...I have 68 that 6 months ago had a bad battery so I replaced it. The guy at Auto Zone said my alternator needed to be replaced too, so, trusting what they said that is what I did. I didn't touch it for 6 months but still drove around, no problems, battery seemed to be doing fine. Then last weekend I finally got around to replacing the alternator and when I took it to Auto Zone he said the voltage regulator was bad so I needed to replace that too. So, I did. 3 days later my battery is dead and Auto Zone dude says "well, I don't really trust my equipment - not sure what else could be wrong". Grrrr. I thought I rewired everything exactly as before - but, now all of the sudden I am getting the 'gen' light on when idling but goes away when I accelerate. Still, my battery is dead so I don't imagine I'm charging. So...first question is, did I really need to replace the alternator if it ran fine for 6 months? Second, what might have happened when I replaced it? Third, this is my first classic so I'm learning as I go - should I stay away from advice from Auto Zone (because they sure are pissing me off right now!). Thanks!

Curtis,
First thing that comes to my mind is the tension of the alternator belt.

David F.

Thanks David...I'll try the belts to see if tightening helps. Also, the original wiring had a ground near the alternator taped up. Should this actually be attached to anything? Looks like the alternator has a spot to hook it on there if required. See the picture where I removed the tape around it, but it remains unhooked.

Hey Curtiss, thanks for joining up. I'm Jim, nice to meetcha!

Put your old alternator and voltage regulator back on the car, doubt there was ever anything wrong with them.

The problem you are having now, gen light on at idle, is just plain low charging system output. The system is working, but not very well. Hopefully going back to your original good parts will fix that.

Do you have a voltmeter and know how to use it?

If you look at the main menu (gray bar above) there is a document downloads button. I really really gotta organize them, but under electrical, on page 5, is a very nice diagram of the charging system.

Only 3 wires go to the alternator, red, white and blue. There wasn't originally a ground. It grounds through the mounting bolts.

Come back soon, we'll get this fixed.

Thanks Jim...nice to meet you as well. Glad I found you guys!

Unfortunately, I only have the old voltage regulator. I exchanged the old alternator in for the core value. Learned a lesson there...hold the old equipment until you know for sure. Should I switch out the old regulator anyway?

My brother has a volt meter and is bringing it by soon...so, that should help.

Question about the red, white, blue (can't tell by looking at the diagram)...should the white or blue be next to the red? Right now (as you can see in the picture) the blue is near the red. I think this is right as when it is switched the 'gen' light stays on the entire time even when accelerating.

I'll leave off the other green wire you see in the picture now and just tape it up like before.

Did you check the belt tension as David suggested? Is the belt shiny on the inside, like it's slipping?

The red wire has a ring terminal and goes on a threaded stud.

The white and blue are a plugin connector, the correct alternator for your car has the terminals next to eachother like this ||

An alternator for a car with the regulator built into the alternator and no separate regulator has the blue and white end to end like this - -

Sometimes these old cars get converted, and it can get confusing if it happened before you had the car.
Sometimes when people convert them they leave the regulator in place, and then it can get really confusing.

It does sound like you have all the right stuff tho, it's just not working very well. Need to get a volmeter on it and do some checks. Also need to verify which type of alternator they sold you.

The white wire should be closest to the red one.

Hey guys...in the end, I ended up redoing the wiring from the alternator to the voltage regulator (and replaced the new regulator with the old one!). Some of the wiring was loose and poorly spliced. It ended up working and now I'm back to functional!!

Glad to hear it!