Ive been having an ongoing issue with the charge on my car being low. If I turn the a/c on it gets a lot lower and sometimes into the red. I tried repacing the alternator with a higher amp unit, but still have the same issue. Im convinced both alts are fine and the problem lies elsewhere. What else could it be? I also was told to check the fuse for the fan, It is fine. Any ides? these headlight dimming gets annoying

 

it is very possible to get a bad alternator, even if you buy it brand new. is your battery fairly new? as your car runs it recharges the battery, which puts some draw on the electrical system... go to your local auto store, and have them test both while running and see what kind of voltage you are getting...should help determine the culprit.

 

Im pretty positive its not the alternator and that it is another componet of the charging system. I just need ideas on what to check.

 

Bump

 

Double check your alternator ground and your block ground. A bad ground will cause your car not to charge to it's full potential. Check your battery ground too.

 

Common problem on all third gens but you seem to have it alot worse than others, Most or even all factory replacement alternators deliver full amperage above 1200rpm depending if it is the stock pully size, but at idle in gear your alternator will only deliver 30-40% of amperage potention, if you have underdrive pullies this could be making the issue worse. you can try and find a smaller alternator pully that will speed it up and give you more power at idle.

 

I dont have underdrive pulleys and I dont think the actual alternator is the issue, I think its another componet of the charging system.


Ok the battery to pass head ground is good. I See the ground on the firewall I just gotta figure out where it goes to on the head.

On the Alternator pigtail that plugs in the back side of the alt. there are 3 wires that go to it, Red wire shows voltage, brown with stripe shows voltage then the last wire is solid brown and no voltage im assuming the third one is a ground is that right? DO you know where it goes to?


Here is the plug im talking about

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Didnt see this post before, The battery is a little over a year old. THe guy at autozone said it was my alternator but with both alts doing the exact same thing I dont think its that. What are the chances of it being a deadcell in the battery?

 

Deleted my post. Everything I suggested I just saw you had already done.

 

In this thread the guy had the same issue https://www.thirdgen.org/forums/elec...ight=dead+cell

I think im gonna try what he did heres what he said

Before I left off, I had narrowed the problem to the brown/white wire I spoke of earlier (which goes to the middle pin on the weather-pak). Some continuity checks showed that the wire is broken somewhere between the ignition switch and wherever it taps off and goes to the fuse box. I ran a wire from an "IGN" tap in the fuse box out to under the hood. Took continuity across that and the brown/white wire where I snipped it earlier... good. Voltage check on the extra wire, key in "ON"... good. Voltage check on brown/white wire... bad.
So I ran the extra wire through a grommet in the firewall, routed it to the weather-pak, and charged the battery. Once all that was done... hit the ignition. Car fired. Checked voltage at battery... 15V! Works like a champ.
This'll stay in place until I swap the motor out for a 383.

 

Disreguard my last message for now



Ok learned a little more about those 3 wires through various diagrams. The smaller red wire goes to the starter and has a fusible link down by there, I am told that it is possibly blown which could cause my problem, Im gonna check it out when time allows. The brown/white striped wire goes to the fan fuse, which I assume is to test the voltage drop with the fan on to kick up the alt. If its not doing its job it woudl explain the voltage drop. then the brown wire goes to the voltage gauge, I think the reason the brown didnt show voltage in run is becasue the car wasnt running and the gauges dont function until the car is actually running, I will verify this and see if thats right. Now that ive got those sorted out I need to test the actual voltage at them and see if one possible has a short.

Another thing I read to do is disconect the ground strap on the firewall and clean it and reattach.

Hopefully chasing these few things resolves my issue.

Any other ideas or suggestions please throw them out there.

 

I am not sure you understand the true purpose of each of the wires on the alternator. I have been looking around and it becomes somewhat confusing because there are a variations such as wire colors, number of wires, etc.

My take is that if there are three wires going to the plug and one wire going to the POST this would be called a '4 wire' alternator. So let us accept that unless told otherwise.

The large RED wire that connects to the POST eventually terminates in a place where we want the alternator voltage to connect. That COULD be the battery but many times it a is 'wire cluster' connection. One of the wires in the cluster would eventually reach the battery.

The smaller diameter RED wire I believe is the 'voltage sense' wire. It is connected to a point that we would want to monitor. The voltage sensed here is sent back to the alternator and the alternator adjusts to keep the voltage at the end of the 'sense' wire to a specific voltage. This connection point we want to monitor COULD be the 'wire cluster' connection point. If it is placed here we are saying ''I do not care what the voltage is at your alternator POST or the positive battery terminal. I want you to adjust yourself to set the voltage at THIS point to the proper voltage. I do not care how much voltage you are dropping between yourself and THIS point. Adjust yourself to set THIS to your designed 'target' output voltage.''

One wire goes to the gage. I do not know the proper color wire to use.

One wire is the source of voltage (for the 'stator'?) to the alternator derived from something associated with the ignition system. It appears to me that this wire is expected to have some type of 'resistive wire', or resistance, or meter with resistance, etc. that was designed to be there. I saw some comments that if the wire is connected directly to the ignition system (without some type of resistive element in-line) that the alternator will eventually 'go bad'. I have no personal experience in this area but it is something to investigate.

So that is my understanding of how the wires interact with the alternator and if it is accurate it might help you visualize what is going on when trouble shooting.

Here is information discussed about ONE vs THREE wire alternators. Kind of hard to understand until you read it a couple of times. If you have a pretty good idea how the alternator works it is easier to understand what the writer is trying to tell you. But interesting read. Remember I think your alternator would be called a FOUR wire alternator. So the discussion lacks some of your wires. His point seems to be that there are good reasons to make the alternator interact with a 'wire cluster' point.

http://www.madelectrical.com/electri...reewire2.shtml

Also, after you make a 'good ground' it is wise to coat it with something that protects it from the elements. Maybe spray on some of the battery protection stuff and let it run down and around your good ground or at least coat it with grease.

 

I have a pretty good understanding of how it works. There is no argument that it is a four wire alternator, I think you where confused of what I was saying, I didnt speak of the wire to the alt to the bat because I already rulled it out of be the problem, thats why I was talking abot the 3 wire pigtail on the back of the alt.

I understand the function of the other wires, I was just saying where my haynes manual said they go to.

 

Just got done messing with it fot an hour or so, I just rulled out the pulley and the belt possibly issue. Its starting to frustrate me badly, but I did figure out something very strange. I let it run until up to temps and once the fan kicked on my voltage went to nearly normal and out of the red, I though it was maybe a fluke so let it cool and did it again and it kicked on again after that, so im assuming its a wiring issue I just dont know what to check at this point. any ideas?

 

I think there is a switch that actuates the fan when it reaches a certain temperature. Maybe you should UNHOOK that switch and when the car is cool, start the car and see if your voltage immediately stays in the normal area (not the red area). If it does then maybe the switch is bad.

But do not let the engine run long enough to NEED the fan on. Just run it long enough to see if unhooking the switch helps with your problem right after starting the cool engine.

 

Yeah it has a switch. I will give it a shot

 

It would really help you a lot if you had a digital multimeter. When you have the problem present, measure the voltage drops between engine ground - chassis ground - & battery ground. Then measure the drop between alternator positive and battery positive. There should not be more than 200mV over any of these 4 wires.
If the drops are ok you measure the full battery voltage which should be 14.4V give or take a few tenths. If this is stable then the problem is in the power wiring leading into the car. Follow them here: www.geocities.com/vtcamaro/Wire-Diagrams.html