Help with Charging System upgrades

[glitch340]

So why isn't the alternator putting out any voltage when both field terminals have ~10.9 volts going to them? If the field terminals are both giving off voltage, shouldn't it activate the alternator to produce voltage and therefore increase the voltage at the bat terminal on the alternator? I'm still at a loss.

[Bullitt-]

Check your voltage regulator...#s seem low

[glitch340]

Yeah, I picked up an FSM, and I've gone through that portion of it. I've also replaced the voltage regulator. I think there must be a voltage drop somewhere between the voltage regulator and battery, but if thats causing a low signal to the regulator, it should be making the alternator overcharge, but it's not charging at all. If I disconnect the bat cable from the alternator, it reads only .4 volts or so. I've take multiple electrical engineering courses only a few years ago, and I still can't figure this one out. Sorry if it's question after question, I'm just at a loss

[Bullitt-]

Put a jumper from the battery to the input of the basalt resistor...you'll be bypassing all the possible wiring issues up to that point.

[glitch340]

Hey, great idea, I'll give that one a try, I'll have the car already turned to on before I do it. I think it'll help diagnose that part. Thanks again bullit! Any idea why it wouldn't be causing the alternator to overcharge? I'm still thinking the voltage regulator must be bad, but I've gone through 2 of them

[Bullitt-]

The voltage regulator needs more or less full voltage (or amperage, I can never keep those straight) to operate I suppose... I've read that upgrading to a high output alternator can cause the regulator to not sense the charge level of the battery, there's a workaround involving a relay.

[glitch340]

Well if all else fails I have an extra 12 volt relay hanging around, but I'd like to get any connections that aren't working properly fixed up first. I'll give these things a try tomorrow or over the weekend. And post back up and let everyone know the outcome.

[Bullitt-]

No they are both hot...one energizes when the car is running the other when the regulator senses the battery needs charging. 

After reading the testing procedure for alternators in the manual I'm sure I was wrong stating what I believed to be true...Apparently the Green lead is a ground provided by the regulator.
  So I believe that the energizing of the alternator you caused shows that it is good.
     Sorry for any confusion I may have caused.

[glitch340]

Okay, that makes more sense because if both leads read the same voltage, there won't be much current flowing through the alternator... So that means for some reason my green ground wire isn't grounding the way it should. the only way I could see it doing that is if the voltage regulator isn't working, but I've tried two new ones with no luck. I'll check through my ignition wire and see if I can get that reading a full ~12 volts same as the battery. Then tackle the non-ground issue. Perhaps I should start buying my electrical equipment at a different store then CarQuest...

[dodj]

Your VR has a good ground?

[glitch340]

yeah, I thought it could be the ground right at the beginning so I cleaned it up, tested the ground strap, and sanded off the paint on the back of the voltage regulator. Now I'm getting like .1 ohms or less from the voltage regulator over to the negative battery terminal. I think that's all the lower the multimeter wants to go though. Still same issues

[Bullitt-]

Have you Ohmed the wires from the regulator to the alternator?...My '73 has a plug beside the carb in the harness, not used on earlier models.
Did your try the jumper to the ballast?

[glitch340]

I'm gonna give it a try this weekend. I haven't ohmed the wires between the regulator and the alternator, but I removed all the electrical tape, from the bulkhead to the alternator and replaced it with some split loom and fixed any wires I found that had been broken and or bare... I'm going to ohm test all the wires that I can think of that may be involved, and hopefully I can figure something out with it.

[Strawdawg]

Do not disconnect the battery while the engine is running.  This can pop something very quickly.  Do not crank the engine until the regulator is mounted and grounded to the firewall as this can pop the regulator as well.

Jumper from the battery straight to the alternator bat terminal, one field terminal and I on the regulator to eliminate the route thru the key and dash...

Test as shown in Bullit's copy from the manual using a jumper to ground off the other terminal after you start it...

[glitch340]

Okay, so far I tested at the ballast resistor and the bulkhead. Between the battery and the ballast resistor theres a 2 volt drop, so I tested the bulkhead and there's a .8 volt drop from the battery to the bulkhead connector. So I'm assuming the other 1.2 volts is the connection in the bulkhead. The other 0.8 must be in the cab somewhere, perhaps the connector at the base of the steering column.

As for the voltage regulator, if I put a jumper from the battery to the ballast resistor, the blue IGN wire at the regulator obviously has full voltage, but the 'regulated ground' wire is showing like 8 volts or so... I'm still thinking there's an issue with the voltage regulators, but I'm going to clean up the contacts and fix whatever is causing the voltage drop before I worry about replacing that again. This is turning out to be a real PITA