Firebird_Man

Where do I begin. I have been troubleshooting this Alternator issue for at least a year. I have replaced Alternator 3 times in a week. However each time except for the 1st time the Alternator tests good on the testing equipment at both Checker Auto and Napa. I haven't been able to use the car in over a year.

I currently have 2 different alternators that I am swapping in/out of the car while diagnosing the problem.

Legend
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A1 - Brand New Lifetime Warranty Alternator from NAPA

A2 - Rebuilt Alternator (1 that I had from 5 years ago, just recently rebuilt)


Also, I have a brand new battery installed 770 CCA

Standard diagnosis
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Battery lead to Alternator shows 12.5 volts all the time with the exception when the engine is running then if Alternator is charging it shows the same as the dash gauge 14.5 to 15 volts.

Both leads into the pigtail of the Alternator show 12.5 volts when keyed on.
When running, if the Alternator is charging then volts read 14.5 to 15 volts

Problem:
--------
A1 - Will work for 15 to 30 minutes before getting super hot. The bearing starts to squeal and the electonics shutdown. My guess. Alternator is running at 100% all the time causing it to get very hot. With the battery hooked up, the Volt Gauge reads 14.5 to 15 volts until it quits working.
During testing, if I disconnect the battery while the engine is running regardless if the Alternator output is 12 volts or 14.5 to 15 volts, the charging spikes to 18 volts. This is what leads me to believe the Alternator is ALWAYS charging.


A2 - Will work for maybe 15 to 30 minutes or for up to 4 hours. No bearing noise so this Alternator doesn't seem to get hot. When I disconnect the battery when the Alternator seems not to be charging, voltage drops to 6 volts.

I've replaced the fusable links even though the old ones seem ok. There are no fuse problems.

I can go on and on about different scenarios I've tried, but cannot seem to corner this problem. I've even gone so far as to remove the Starter from the electrical system altogether but independently hooking it up to it's own battery source.

Could this possibly be a dash Voltage Gauge issue where it works then builts capacitence and then quits? Has anybody experienced such issues before?

I'm telling you that I'm at Witts End and can't seem to find my way out.

Please help.

Fullsizewagon

It seems you have a multiple fault condition; that is both your alternators are defective. Voltage should be 13.8 to 14.4, no more, no less. It seems you have a digital multimeter, use this as a reference even though your dash gage seems to be accurate.

A1; should not squeal no matter how hot, and should not output 18V w/o load.

A2; should not put out only 6V W/o load (how is the ignition able to work on this voltage anyway?). Has the rectifier been replaced btw?

I don't know how comprehensive those Napa tests are, but it seems to me you'll need to get A1 replaced, and/or A2 properly fixed.

sofakingdom

iTrader: (1)

Sounds like the "sense" lead isn't connected.

Look at the small plug. There should be 2 wires; brown, and red (brown should be closer to the output stud where the big thick wire goes). The red one is the "sense" lead, the one that tells the alt what the system voltage is. The regulator tries to adjust the alt output to maintain that wire, which is to say the point in the electrical system that it's hooked to, at whatever its setting is (14.2V or whatever). If that wire has 0 volts on it, the alt will go to ABSOLUTE MAX ***** TO THE WALL, and will NEVER EVER STOP as long as it's spinning.

Check the voltage on that wire with the key On and the engne not running, and then with the engine running. What is it?

The brown wire goes to, among other things, the bulb in the dash. The dash bulb, for reasons outside the scope of the issue at hand, is labelled "Choke". Does the "Choke" light come on when you turn the key to On with the engine not running?

Firebird_Man

Let me start off by thanking those that have replied.

Next let me say that I know this problem seems to defy logic. I've worked on Alternator electical problems before and never have I experienced something so mind boggeling.

Yes, I had/have verified that the voltage coming off the alternator is indeed between 13.8 - 14.4 volts using a digital Multi-meter (and a analog one too)

When cold (that is Alternator is cold), the charging system seems to function properly...but once it warms up it stops charging. When I see the charging stop, I'll check the temp at the alternator pulley. It is way to hot to touch. I'm about to go buy and infared sensor to know how hot it really is getting.

Now I have experienced a condition where the alternator will charge for a longer period of time...lets say 2 days...maybe 50 miles of driving. However I have had it running and can get it to fail relatively quickly buy letting the engine run for about 15 minutes, then stop/start the car 2 or 3 times with the headlights on. Upon one of those times, the alternator will stop charging and may or may not beginning charging again when it cools down (even waiting a day between using).

Like I said this is the 3rd Alternator from Napa Auto, and this last time I have upgraded to Premium, which means it has a lifetime warranty.

Now to answer the Brown/Red lead (which the new pig tail is Red/White).
The question I kept asking around was, which lead should be hot at all times and which one should be the sense lead (the one that turns on the alternator field)? Can't seem to get a good answer on that.

The Brown lead which goes to the 'Choke Heater' relay is currently not plugged in. I have replaced it with a keyed on source. Reason: Another mechanic told me to do this because this always seemed to be a source of alternators to failures, assuring me that once I did, my problem woudl be solved. I also asked him which lead sould have constant 12+volts at all times and which lead should be the keyed on source, he said to make them both the same by connecting both leads only to a keyed-on source. This sounded good talking about it, but in reality I was no better off then how it was originally. This so called 'Choke Heater' relay keeps switching between 6 volts and 12 volts...6 volts to feed the Choke Heater and 12 volts to keep the alternator happy. At one point I replaced the 'Choke Heater' relay with one purchased from Checker Auto. It was at that point I found that my real problem was the 'Alternator' (This was a couple of years back).
Well I haven't driven this car in a few years and would like to start driving it on a regular basis, but can't because of this charing system problem. Well the original 'Choke Heater' Relay was tossed two years back, so I don't have it anymore.

The other curious thing I had read was I have 2 different repair manuals for the 82 Trans Am...in one manual the spot for the 'Choke Heater' relay is acutally labeled 'Charging System' relay. Whats up with that? Could the relays actually be different and could actually be at the heart of my problem?

Thanks for reading/responding.

Best regards, and my hair is greying daily.

Jproz1167

iTrader: (3)

if you tossed the choke relay thats why it's doing that. somehow the choke light is tied into the alternator. everytime Ive had a alternator dying o a 4barrel engine the choke light has come on.

Firebird_Man

Well I tossed the original in favor the the new one. I was just wondering if there is a difference between 'Choke Heater' relay and 'Charging System' relay. However, I called the dealership and they had never heard of the 'Charging System' relay. They told me if I could read the part number off the relay they could get me a replacement...I had already thrown it out months before. Again I say there is a relay there...the OEM one.

I guess it's time to find a firebird in the junkyard and steal its 'Choke Heater' relay.

DirtyCanadian

where do you find this relay and where is the rectifier? on a 3rd gen particularily an 83 trans am?

Fullsizewagon

The relevant wiring diagram (for an '84 T/A) can be found in this tread:
https://www.thirdgen.org/forums/elec...ights-dim.html
It says the relay is in the convenience center (under dash).
The rectifier is inside the generator.

Firebird_Man

The relay on my 82 T/A is in what is called the Convenience center located under the dash. You'll need to remove the protection cover under there and then look for it over by the accelerator pedal. I had to unclip the convenience center as it is snapped up in place similar to how the fuse box is configured.

Oh and btw; I replaced the relay I had with one I found on a T/A in the boneyard. I've also gone thru the wiring, replaced the dash panel gauge cluster, and still I have the issue...so now I only drive the car during the day and for short distances.

lol

DirtyCanadian

just so you know many new alternators new in the store are remanufactured, and are faulty I am kinda wondering if my brand new alt is hooped too. the car isnt getting power from alt at all