72 Alternator wiring.

[USatC]

Just realized my battery wasn’t charging and noticed that the alternator has NO lines connected to it. Harness is kinda cut. Anyone have pictures of their 72 alternator wiring or a wiring diagram for this year SB Satellite? I attached some photos of my problem and what i think might be the connections for it.

 

[Nacho-RT74]

no need for pics... just need to know should be getting one green wire coming from reg ( regulated ground ) and one blue wire coming from ign switch ( constant positive )

If any of those sources is missing, you won't have anything feeding the rotor fields to create the magnetig field the stator will capture to source the power.

 

[Nacho-RT74]

even this wiring diagram includes ignition section, you need just to take care of the alt and reg wires:

prongs on alt can be feeded reversed, doesn't really matter, as far BOTH are correctly isolated from alt chassis

 

[Nacho-RT74]

OH, and of course, thick gauge black wire ( stock is 12 ) eyelet terminal FROM ALT POST UP TO AMMETER, factory did through the bulkhead. that's the positive output to the system. Negative goes through chassis/body

 

[USatC]

OH, and of course, thick gauge black wire ( stock is 12 ) eyelet terminal FROM ALT POST UP TO AMMETER, factory did through the bulkhead. that's the positive output to the system. Negative goes through chassis/body

So what runs to this point? The thick black wire?

 

[USatC]

OH, and of course, thick gauge black wire ( stock is 12 ) eyelet terminal FROM ALT POST UP TO AMMETER, factory did through the bulkhead. that's the positive output to the system. Negative goes through chassis/body

So what runs to this point? The thick black wire?

 

[mrsnicks]

So what runs to this point? The thick black wire?

Yes.

 

[Nacho-RT74]

yes, but without the other ones, that stud won't have any juice coming out from it

 

[USatC]

Yeah so i got them all connected and i have a slight issue. My baterry is reading 16-17 volts now that the alternator is charging it. With the lights on it’s an acceptable 14 but otherwise it is overcharging. The voltage regulator is new. Any ideas?

 

[Nacho-RT74]

whats the batt conditions ?

Bad wiring conditions between ign switch and regulator can get more voltage too. Bad ground too.

Internal short on alternator too. I got once 24 volts and no charge. In my case one of the vent vanes of rotor getting friction with one of the stator leads to the diodes bank. everything looked fine on bench, but the fail came out when spining on engine ( that was hard to find )

 

[USatC]

So i have everything hooked up and the battery will charge. The issue now is that it won’t continue to charge. When i i try to drive the battery voltage drops down to 11-12 volts and stays there. I had the alternator bench tested and it tested good. When it’s running if i pull the positive battery cable the car dies instantly. But it will gain voltage sometimes as if the alternator is charging it...

 

[Bb70charger500]

Just because the regular is new doesn't mean it's good !

 

[Nacho-RT74]

welll the alt you have installed is a lates 70s and laters one, which usually the smaller puts out around 60 amps at max output ( stator is wider than earliers ), from the 40-50 earlier squarebacks got. That should be quite enough to hold the car at iddle with disconnected batt without any extra load ( earliers usually stalls the engine making that ), BUT also depends on the pulley it got.

I'd still check for wiring conditions. The wiring you shown don't tell me the rest are really good to trust on it. have you atually unplugged the engine harness bulkhead plug ? ign plug down the column ?

Damaged regulator, or bad grounded unit are still something to check.

You can also full field the alt at the brush you are plugging the green wire with a jumper wire to ground, to check for changes.

EDITING... you can full field the alt grounding the green wire at regulator plug with unplugged regulator. That will test the wire itself.

 

[USatC]

welll the alt you have installed is a lates 70s and laters one, which usually the smaller puts out around 60 amps at max output ( stator is wider than earliers ), from the 40-50 earlier squarebacks got. That should be quite enough to hold the car at iddle with disconnected batt without any extra load ( earliers usually stalls the engine making that ), BUT also depends on the pulley it got.

I'd still check for wiring conditions. The wiring you shown don't tell me the rest are really good to trust on it. have you atually unplugged the engine harness bulkhead plug ? ign plug down the column ?

Damaged regulator, or bad grounded unit are still something to check.

You can also full field the alt at the brush you are plugging the green wire with a jumper wire to ground, to check for changes.

EDITING... you can full field the alt grounding the green wire at regulator plug with unplugged regulator. That will test the wire itself.

Yes i have. I think i have all thE wiring corrected.

 

[USatC]

Just tried a new voltage regulator and now it’s overcharging. The voltage changes relative to the rpm of the car so when it’s revving high the voltage is too high which is what the voltage regulator should be controlling

 

[USatC]

welll the alt you have installed is a lates 70s and laters one, which usually the smaller puts out around 60 amps at max output ( stator is wider than earliers ), from the 40-50 earlier squarebacks got. That should be quite enough to hold the car at iddle with disconnected batt without any extra load ( earliers usually stalls the engine making that ), BUT also depends on the pulley it got.

I'd still check for wiring conditions. The wiring you shown don't tell me the rest are really good to trust on it. have you atually unplugged the engine harness bulkhead plug ? ign plug down the column ?

Damaged regulator, or bad grounded unit are still something to check.

You can also full field the alt at the brush you are plugging the green wire with a jumper wire to ground, to check for changes.

EDITING... you can full field the alt grounding the green wire at regulator plug with unplugged regulator. That will test the wire itself.

Any thoughts on my most recent comment?

 

[Nacho-RT74]

My thoughts keep being the same:
Damaged battery
Damaged wiring
Bad ground at reg
Not good reg

And once again I keep saying the same to all ppl. If everyone checks further the old tired and mostly of the times ABUSED and hacked 40+ years wiring like takes care of steering or fuel system, many of electrical troubles will be part of the past, and less threads about this will appear.

After check what you found to feed the alt, I have serious doubts about the rest of the wiring health. Being that the problem of this specific topic or not, please check wire by wire of your car. Its time to do it.

Any resistance due dust, rust, loose section, will produce a decay on voltage and if reg takes that poor signal will try to compensate. Assuming reg is good of course.

If main paths are damaged, everything will be bad sourced and will take more power to beat the resistances of the system. So, that could be a reason of the high voltage readings, bad reference signal to the reg coming from anywhere... ammeter related wires ( amm itself, bulkhead ), ign switch plug down the column, bulkhead itself... and when gets enough power to beat the fails you get what you are getting. It's just a guess.

 

[pjm8047]

Right from the 72 service manual