1985 Pontiac Firebird Alternator dying again

Tiny
AXL4U2000
  • MEMBER
  • 1985 PONTIAC FIREBIRD
  • V8
  • 2WD
  • AUTOMATIC
  • 60,000 MILES
Hello, This is my third alternator in this car. I had it replaced when I first bought the car because it died one day and I was told it was not charging the battery. The second time I had it replaced because I was getting very low readings on the gauge in the dash ( I know the gauge is not totally accurate it may be off 5 volts or so ) and I replaced that one because it stopped charging my battery again causing a dead battery. I decided to put one on my own and I bought a 108 amp thinking my mechanic was putting the wrong one. It started working perfectly but now I am noticing low readings again and it has been perhaps 2 months since it was replaced last time. Just like the two past occurences. Someone told me I may have a short and I did some testing and I think I found a short in the CTSY WD circuit but even after removing the fuse it will give me low readings. Not to mention that also this is the second time in less than a year that I had to replace the ignition module in this car. Battery cables look good and I have replaced the coil, rotor, cap and capacitor in the distributor not to mention new spark plug wires also so I am lost. Can you tell me what I can do to find out whats wrong and prevent for this to happen again?
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Wednesday, July 15th, 2009 AT 9:58 AM

20 Replies

Tiny
BUDDYCRAIGG
  • EXPERT
While I can't say that I have THE answer for you, I do have a couple of suggestions.

That plug on the side of the alternator, unplug it and plug it back in a few times. It may have some corrosion on it, and everytime you change the alt, it gets some of the corrosion scrapped off and will work for a while.

Second, make sure the place that the ground cable attaches to the engine is clean and tight.
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Thursday, July 16th, 2009 AT 2:53 PM
Tiny
AXL4U2000
  • MEMBER
The connector in the back of the alternator is clean and tight. There is some power steering fluid at the ground connector with the engine. I cleaned it a while back and althoguht I know I have a leak on the resevoir of the steering pump how is that area supposed to be clean when it is under the car? You mean remove the wire, clean tthe surface and put it back together? Also why is my ignition module dying around the same time my alternator is?
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Thursday, July 16th, 2009 AT 3:56 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Yes, that's what I mean.

Possibly a problem with the ground, the problem with the module is the reason I mentioned it.
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Thursday, July 16th, 2009 AT 4:36 PM
Tiny
JACK42
  • MEMBER
I agree, a poor connection at the ground can cause the issues you describe. What kind of modules are you using? Cheaper is exactly that. Cheaper, same goes for the alternators.
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Monday, July 20th, 2009 AT 9:43 AM
Tiny
AXL4U2000
  • MEMBER
I checked the battery cables and connections and cleaned them but the problem still there. I am using a lifetime warranty alternator that I bought a Kragen same with my modules. The alt was about $130 for a 108 volt and about 30 bucks for the module. All I know is that there is something in my car that is killing all three ( battery, alt and module ) around the same time and it is doing the same thing all over again like the past times. I noticed the following just in case this may help: 1- the voltage drops each and every time my cooling fan comes on. Problem seems to increase when the weather gets boiling hot. 2- I removed the fuse for the radio and this won't kill it. I started to remove fuse by fuse with the 12v test light attached to the battery post and when I removed the CTSY WD fuse the radio died. I checked all connections for that circuit but couldnt find anything. 3- some ( well most of them ) of my dash warning lights don't work. I can see the engine light when I put the key in the ignition but thats about it.
I know the alt will go bad if the battery is going bad since the batt. Will demand more power from the alt to be charged but the question is what is making the battery go bad? This is my second battery in a year and by the way it looks it may be a third one coming very soon.
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Monday, July 20th, 2009 AT 12:52 PM
Tiny
JACK42
  • MEMBER
If you are checking for a draw, the key has to be off, along with everything else in the car and the door switch needs to be taped down so the interior lights arent on. If the draw does kill the battery in that length of time, you may need to have a shop that specializes in electrical look at it, since it is such a small draw.
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Monday, July 20th, 2009 AT 3:05 PM
Tiny
AXL4U2000
  • MEMBER
I think the problem is the gauge itself. I tested the battery at the post and I get a solid 14.36 with the lights on. With the fan and the lights on I get 14.16 while in the dash the gauge reads 11-12 volts. Battery is at 12.5 before car is running while gauge is showing 10 volts.
I was not expecting you to fix my car over the internet and I do know I have to take the car to the professional. All I wanted to get was a possible cause so the mechanic will not rip me off with some mickey mouse reason to take my money. If your answer was pointing at something I could do myself, then even better.
Thanks for your help.
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Monday, July 20th, 2009 AT 6:03 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Is your radio aftermarket?
Maybe someone taped into the wrong wires.

How long does it take for your battery to go dead?
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Monday, July 20th, 2009 AT 6:37 PM
Tiny
AXL4U2000
  • MEMBER
You know what? I was thinking the same thing. When I bought the car it had a sony stereo and they left the wires for the amp unhooked from the battery and I found some more loose wires in the jack compartment. I still can see some red and white coaxial wires underneath the radio in between the center console and the radio console. I guess the only way to find out will be to remove the stereo and have someone take a look rite?
Well see the battery in the car ( the one that came with the car when I bought it ) died maybe 3 months down the raod. Then I bought another one and it last me about 3-4 months then this is the scary part. It has been 3 months since this last one and I think it is doing the same again.
I tried to disable the radio most of the time ( by removing the CTSY WD fuse from thne box and that seems to have worked but I end up hooking up the radio again
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Monday, July 20th, 2009 AT 6:52 PM
Tiny
BUDDYCRAIGG
  • EXPERT
I meant, does the battery go dead if you let the car sit for a day, a week, a month?

And about your radio,
you should have an orange wire that is hot all the time. That keeps your memory.
And a yellow wire that is only on with the key.
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Monday, July 20th, 2009 AT 6:56 PM
Tiny
AXL4U2000
  • MEMBER
My bad. I had never left the car without using it for no more than maybe 3-4 days and it always start. But one time I went to work in the morning, car started fine and all and when I was leaving in the afternoon around 5 the battery was totally gone like no juice at all. The second time, going to work again but at 4 am I had my headlights on got to work and went back home at 5 pm. Two days later w/out starting the car the battery was dead, no juice at all.
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Monday, July 20th, 2009 AT 11:57 PM
Tiny
BUDDYCRAIGG
  • EXPERT
A fully charged battery has 12.6 volts.

So far your readings are suggesting that the alternator is working.

I find it difficult to believe that you have had 2 batteries fail every 3 months. Maybe something happened with the car and drained the battery so that it was discharged. But the battery wasn't at the end of it's life.

Right now, it seems that everything is working correctly.
Unless you haven't mentioned something about your module.

The next time you have a problem with the battery or the module, or the alternator, come back here and tell us about what's going on.
And we'll help you get to the bottom of it.
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Tuesday, July 21st, 2009 AT 12:34 AM
Tiny
BUDDYCRAIGG
  • EXPERT
OH.
PS

The body style of firebird you have and the one before it, has a history of having a problem with the body of the car not being grounded correctly.

I've seen the shifter cables get welded solid, cause that was the ground circuit when you tried to start the car.

With your volt gauge reading incorrectly, it suggests that you may have that problem too.
Try adding a couple of ground wires from the engine to the body of the car.
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Tuesday, July 21st, 2009 AT 12:38 AM
Tiny
AXL4U2000
  • MEMBER
I will sure try that. On a side note yeah I have a problem with the ground since only my engine light comes on when I first put the key in the ignition. All other warning lights are fried.
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Tuesday, July 21st, 2009 AT 8:25 AM
Tiny
BUDDYCRAIGG
  • EXPERT
Your other warning lights should only come on when you have the key in the CRANK position.
It's called the "bulb test"
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Tuesday, July 21st, 2009 AT 9:18 AM
Tiny
AXL4U2000
  • MEMBER
I know but they wont.
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Tuesday, July 21st, 2009 AT 10:30 AM
Tiny
BUDDYCRAIGG
  • EXPERT
I misspoke.
All of these lights (if you have them) will come on with the key in the ON position and the engine off: alternator, oil pressure, check engine.

The temp, and brake warning lights come on when you are in the CRANK position.

All of them, except for the ECM are grounded to the body.

It's unlikely that they are all burnt out. So checking for grounds will be a good start.
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Tuesday, July 21st, 2009 AT 10:43 AM
Tiny
AXL4U2000
  • MEMBER
Ok I installed a separate gauge in the dash to monitor the voltage. It was going well but I noticed the following: Once I turn my signals the voltage drops each and every time the lights blink ( meaning the needle in the gauge drops every time the light blinks in a perfect coordination). Other than that stays on the 14 volt range with minor variations and yes sometimes gets down to 13 volts but only with the fan and signal lights on. Is this normal? I was thinking that if the voltage drops means the alt has reached max capacity and can not generate more to keep up the 14.5 volt.
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Tuesday, July 21st, 2009 AT 2:47 PM
Tiny
BUDDYCRAIGG
  • EXPERT
Everything you said is normal.
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Tuesday, July 21st, 2009 AT 4:27 PM
Tiny
AXL4U2000
  • MEMBER
Awesome!
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Tuesday, July 21st, 2009 AT 4:56 PM

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