83 Delta 88 Alternator Wont Charge

Chris Tomas

Chris Tomas

Apprentice
Jan 6, 2018
60
12
8
#1
How i do i write this as briefly as possible? I wish i knew.

My alternator simply refuses to charge. It'll keep the battery around 12.6 volts with no accessories on :/

The original alternator if i recall right did at one time output around 13.7 volts back it was being driven heavily in summer 2016.

Well, that was back when i didnt lose the only set of keys like a moron and didn't have to hotwire it,which it now is...

Fast forward to 2018 and the battery doesn't charge as stated before, 12.6 volts when running. I can unplug the battery and charge it overnight with an external battery charger, itll test to around 12.8v, and as soon i try running the car she starts to drain.

In November 2016 the alternator belt had snapped, but was replaced in February 2017 i'll add.

I don't believe its my hotwiring job,nor the belt because prior to it being towed to my new place in August 2017, it was able to drive down the alleyway ok. Now she barely wants to move and runs hella sluggish, in fact when i put her in drive she struggles more.

Heres what I've done so far for diagnosing:

1.Checked with a meter battery voltages when off and running (never goes past 12 volts)
2. Checked alternator with a meter when running, still reads an output that the battery does, 12ish volts.
3. Replaced the original alternator with 2 different ones, same no charging results.
4. Used original wire connector for alternator with same results.
5. Hacked off original wire connector and wired on the ones that came plugged in the replacement alternators, same result.
6. Removed neg bat cable while running after 1st alt replacement- car doesnt die but lights were VERY dim in dash. Meter measured 7 volts.

I should mention with the original alternator and 1st replacement, my charge light would normally turn on as normal when accesories
were applied, and turn off after the engine was running. However, the 2nd alternator which i tried installing today, it now keeps the charging light CONSTANTLY illuminated even when running now, with occasional flickering of the charge light. Giving the engine a good rev doesnt help.

Voltage regulators are internal on the 12si alternator, so i dont see externally a problem there.

And both of the 2 alternator swaps yielded same voltages (however the 2nd swap now gives me a charge light when running too now, the other original and 1st swap only did when it wasn't),. Both are original Delco Remy parts pulled from cutlasses...

Could it be a partially burned fusible link? I can put my meter on the alt and itll match the battery voltage wise.

Could it be a bad fuse in the fuse box? I don't recall having an alternator fuse....

I will mention i wired up an aftermarket stereo as well, but i have the unit unplugged at the moment for testing.

I'm REALLY tempted to just directly wire the battery to the alternator and skip the wiring harness, but it needs to be fused and i have no idea how to begin with that.

If i gotta replace the alternator a 3rd time, i'm sure the junkyard will do one more warranty replacement, but i'm hoping someone can tell me how to test the alternator so i know its good this time before i spend the day to cross the city and take it on the train home....

Hopefully someone can give me some insight here, cheers!
-Chris
 
Last edited:
DRIVEN

DRIVEN

Geezer
Apr 25, 2009
5,735
5,485
113
Owyhee County
#2
Take it to a qualified tech.
 
Chris Tomas

Chris Tomas

Apprentice
Jan 6, 2018
60
12
8
#3
Take it to a qualified tech.
I might if i wasn't limited to my disability welfare funds, but to be honest i'd rather learn how to work on the vehicle. Its an educational experience to me.
 
Wageslave

Wageslave

G-Body Guru
Jan 25, 2017
863
957
93
#4
Try running a jumping wire from the 1 terminal on the two pin connector to the big charge wire. This should full-field the alternator and make it charge if it is able. If it does not charge then alternator is boned. If it does charge, then there is something wrong in the excite circuit on the car.
 
DRIVEN

DRIVEN

Geezer
Apr 25, 2009
5,735
5,485
113
Owyhee County
#5
Honestly, I had trouble following your description. Jumping #2 post to the batt post will excite the alternator. If you get 14v +/- (measured at the batt post), the alt is okay. If not, check the wiring.
 
Chris Tomas

Chris Tomas

Apprentice
Jan 6, 2018
60
12
8
#6
Try running a jumping wire from the 1 terminal on the two pin connector to the big charge wire. This should full-field the alternator and make it charge if it is able. If it does not charge then alternator is boned. If it does charge, then there is something wrong in the excite circuit on the car.
Thanks for the reply!

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You mean like this? I initially had the stock plug which didnt have that loop on the back, but then i clipped it out and rewired the new plug on that looks like the one in the picture, no change regardless though. I'll try again in the morning.

What about running the alt directly to the positive battery terminal?
 
Chris Tomas

Chris Tomas

Apprentice
Jan 6, 2018
60
12
8
#7
Honestly, I had trouble following your description. Jumping #2 post to the batt post will excite the alternator. If you get 14v +/- (measured at the batt post), the alt is okay. If not, check the wiring.
Sorry for the long description, but yes i tried doing that ill check my wiring again though. The stock wiring harness didn't have the jumper wire, but the one that came with the alt did.
 
Wageslave

Wageslave

G-Body Guru
Jan 25, 2017
863
957
93
#8
Thanks for the reply!

proxy.php?image=http%3A%2F%2Fwww.zukikrawlers.com%2Falbums%2Fholeshot%2F100_1765.jpg&hash=d2745198d596cd8d968910af92c89f58


You mean like this? I initially had the stock plug which didnt have that loop on the back, but then i clipped it out and rewired the new plug on that looks like the one in the picture, no change regardless though. I'll try again in the morning.

What about running the alt directly to the positive battery terminal?
The #2 terminal is a sense wire for the regulator, and should be tied to the big post like in the picture.

The #1 terminal is the field wire and will energize the coils in the alternator. This wire is usually powered from the run position of the ignition through a light bulb (Volt light) or diode to prevent a back flow of voltage from powering the ignition coil after the key is turned off.
 
Chris Tomas

Chris Tomas

Apprentice
Jan 6, 2018
60
12
8
#9
The #2 terminal is a sense wire for the regulator, and should be tied to the big post like in the picture.

The #1 terminal is the field wire and will energize the coils in the alternator. This wire is usually powered from the run position of the ignition through a light bulb (Volt light) or diode to prevent a back flow of voltage from powering the ignition coil after the key is turned off.
Weird. The stock alternator and connector from the factory didn't have that loop wire from #2. Not sure why.

I'll rewire on that 2 pin connector with the wire that nuts on back again in the morning. There wasn't a change when i tried it earlier but maybe my connections weren't adequate enough.
 
Wageslave

Wageslave

G-Body Guru
Jan 25, 2017
863
957
93
#10
I have seen applications where the #2 terminal will be ran to the ECM as a way to stop the alternator from charging (and the associated load on the engine) when the motor is at full throttle.
 

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