I have swapped out my 305 for a 350. I am having a little trouble with the charging system. I have a new alternator and its not charging. I got it tested and it tested at about 15 amps. I have hooked up the 2 wire plug blk/red to the alternator. The red wire from that harness goes to the return on the back of the alternator??? That is the only place it will reach its maybe 2 inches at most long. The main ground from the battery was attached to the top of the alternator mount. The guy that is helping me said its the best place to put it. I have read in the forums that there may be a wire perhaps brown that comes from the volts gauge and that it needs to go to the alternator also. Where should this wire go there are no other places to connect any wires. There is a bolt on the back of the alternator that you connect the bracket for the long bolt to the motor should i put the ground here or somewhere on the motor? Please help this is the only thing holding me up from getting back on the road. The volt gauge is reading 8-10 volts when i start the car and after it runs for a while and warms up i turn it off it will start let it run for a few more minutes shut it off and it wont start again the battery is too low to turn it over. I also have an extra wire coming off of the positive side of the battery that i dont know where to put it. It doesnt go on the alternator (fire bad)( new alternator and battery on car after that little mishap) it will reach the starter but why would the battery send 2 wires to the starter. The car starts and runs fine with this wire not hooked to anything at all so it cant be very important I dont think. oh yeah the alternator gets extremely hot after the car has been running a bit would that be a problem with not having a good ground to it? would that cause it not to charge the battery if it doenst have a good ground
So in closing where should i put the main ground for the battery? Do I need a connection wire possibly brown going to the alternator and if so where do I put it and what should the wire look like. Thanks in advance for the help

Car is an 85 T/A with vin H lg4 engine stock replaced with 350

Here is a wiring diagram for the charging system but I couldnt figure out exactly what I should have hooked up to what on it and where it should go lol
http://www.geocities.com/vtcamaro/Pi...rams/pg136.jpg you will have to copy/paste the link geocities does not allow direct linking to photos


THx for the help everyone

 

Looks like the brown wire from the altenator connects to pin F8 on the bulk head connector (driver's side fire wall). It is routed to the choke heater relay coil and the volts indicator light in the cluster. Here's the bulk head connector pin out.

 

Delco alternators typically use three wires for operation. I'll post the colors tomorrow I don't have my manual handy. The large wire that mounts with the lug goes to the battery through a fusible link. The plug should have two wires, one goes to the ignition switch the other is a sense wire which also goes to a 12 point. you can achieve ground through the case as long as the engine has a proper ground wire installed to the chassis and the battery has a good chassis ground as well. The sense wire is usually the brown wire. The sense wire is what detects voltage present in the electrical system and adjusts alt output accordingly. It would help to know what alternator you have. Up to about 87 TG's had the 10si unit, later ones the CS series. While they are essentially wired the same I believe the early ones may have used a resistor. I am going from memory, I'll check and edit later.

 

Thanks guys i havent had alot of time to keep up with the boards. Im not sure what alternator i have it is a stock replacement from autozone for and 85 T/A so it should be the same as the one that came off. If the brown wire hooks up to the alternator where would it go. lol There is no where to hook anything else up to it unless it goes to the output nut on the back where the red wire from the harness goes
I will try to take a picture tomorrow and get it up here maybe that would help. Engine compartment is a mess a bunch of wires from the carb that have no place to go now that I have a new edelbrock. I think the red wire from the 2 plug wiring harness goes back through the fusible link to the starter solenoid and then back to the battery? One other thing have any of your cars ever made you want to pull out your hair and scream. The volts gauge works it just keeps going down so its hooked up somewhere to something it starts out at about 12 and after running the car for 20 minutes it is down to 8 so the gauge works? I really need to get the car going sometime this week or I wont have a way to get to work anymore. Its only been parked for 2 1/2 years lol. Maybe the pictures will shed some light on the subject.

 

you can temporarily tie it to the lug on the back of the alt. Ideally it goes to the fuse panel but any spot with 12 volts will do.

 

Ok I think I have it figured out finally.
The plug that connects to the alternator has 1 wire coming from the wiring harness.. Its a brown wire I cleaned the crud off of it and instead of black its brown. IT is the wire that tells the alt to charge the battery when it needs to. The other half of the plug contains a red wire that connects to the output on the alternator. Now comes the part I am still unsure about. The battery needs a wire to run power back to it, looking around the wiring harness the only one that would work is the wire coming straight from the battery it has an eye hook on it and would work perfectly on the back of the alternator. When my friend and i hooked everything up the first time I dont remember if he hooked up the output wire that loops back into the alt but we did hook up the wire to battery and if fried the alt and battery so im kinda scared to do it again. Im going to get someone with a voltmeter to come over and keep an eye on it tomorrow so if it is overcharging we can shut it off. IF you guys think this is right let me know if it is I can drive it to work tomorrow night wooohooo. I will check the boards befor tomorrow again. I dont have time to work on the car today i have to get the babys room ready he will be here in 4 weeks and I still have to put together all of the furniture arrrgghhhh
Thx for all the help everyone
Wesdog

 

Congrats first of all. Yeah, the large red wire with a lug goes to the rear of the alt and is retained with a nut. That should go back to battery through a fusible link.

 

hrmmm....?? none of the wires that connect to the battery have a fusible link. I am hoping that it would be ok without the fusible link. This car is starting to get on my nerves. The wire without the link is the only one that could possibly go to the alternator so as soon as I can get someone over here with a voltmeter to keep an eye on it im going to try it. That may be next week. I dont want to fry another battery/alternator it gets expensive but like I said i think the problem that caused that was not having the wire that connects back into the alternator hooked up to regulate the power going to the battery (at least I think that is what it does). So everyone cross your fingers, say your prayers, and take your vitamins. Maybe it will work out and I can take my hot rod for a ride.
Thx again for all the help guys,
Wesley Jones

 

lets bring this back for a moment.

first off, car is 89' with serpentine, passenger side alt.

<b>The plug that connects to the alternator has 1 wire coming from the wiring harness.. Its a brown wire I cleaned the crud off of it and instead of black its brown. IT is the wire that tells the alt to charge the battery when it needs to.</b>

My alt has 2 wires coming off the plug at the top, and one coming from the back.

the ones off the top are white / red. the one off the back is red and thick.

From what Ive read through searching for an hour now, the white one goes to a 12V ignition source (12v when key on) and the other two go directly to the battery.

Correct or no?

 

Where'd you get '89 from?? Did you mean '85?

Mostly correct - as stated in the prior posts, the large lug on the rear of the alt is the output, which connects to the battery through a heavy gauge wire. The other two wires on the plug are for voltage sense and field turn on. The voltage sense wire connects to either the output of the alt at the back of the alt or to the battery connection at the large lug of the starter.

 

whoa sorry it is an 89 with DRIVER side alt. been a long day sorry.


Ok so wait. which is field sense and which is turn on thingy?

I assume the white wire goes to the 12V (key ON) source, and the RED wire goes to the back of the alternator then? (which is where the battery plugs too)

 

On an 89, the 2 wire plug has a red wire and a wht or tan colored wire. Red goes to key controlled 12 volts, the wht or tan colored wire is the "sense" line. You can tie it directly to the lug at the rear where the battery line connects but the alt won't charge as hard and possibly not maintain the battery enough. The sense line should have a resistor in line or you can use a diode. www.alternatorparts.com has the free online diagrams for the CS alt which gives you the different hookups. When the sense line is at the same voltage as the battery alt output is low. They drop the voltage to the sense wire intentionally so that the alt hit the battery with around 13.5-14 volts all the time. Hope this helps.

 

well let me ask you this danno. I am using a Gel Cell battery, which i am told hates to be overcharged.

would tying the white wire to the lug on the back help it "barelly" charge so that it doesnt overcharge itself?

 

Yes. However, it may not be neccessary. If you use your lights, AC or other devices regularly it should not be a point of concern. Even with a conventional battery the alt only keeps the battery at about 80% of rated capacity. The only real way to overcharge an auto battery is to force charge it by full fielding the alt, or by an external high current charge. The chances of it happening in the car with it's charging system are slim unless the alt develops a problem.

 

Alright danno heres another question... heh...

Today an itiot put the battery in my car BACKWARDS. then proceeded to crank it over....

it blew my MSD ignition up, and my distributor, and poped about 4 fuses.

i have all that crap replaced, and the car runs now... except...

the battery voltage seems to be sitting at 10V, not charging.

Im thinking alternator right? so i replace it, and still not charging.
so i rewire the thing, took the white wire and put it directly to switched 12V, and redid the wire from the lug to the battery and the other red wire. I can hear the alt kick in because when i give it 12v on the white wire the engine RPMS drop. But its still only giving my battery 10V. Its a Gel Cell too.... Should be more than 10V even unplugged i am thinking?

 

Pull the plug on the top of the alt, and with the key on engine off measure the voltage at the 2 wires. One is a heavier guage wire that is the 12 volts switched from the ignition, the other is the sense wire. The heavy wire should read the same as the battery the sense about half a volt lower. Look for a fuse labeled "fan/chg" in the fuse panel, if it popped the alt won't have any sense voltage and won't charge. Also make sure the heavy rear wire read 12 volts with the key off, there is a fuse link between that wire and the battery. If all voltages test OK chances are the regulator IC in the alt was fried. That's about the only time they fail. LOL, Dan

 

well it seems the alt is bad. I didnt do anything you said, because i didnt get a chance.

Today i was driving down the highway, and suddenly my ignition died. turns out the alternator red wire started to pull more than 30 amps and popped the fuse that also ran my ignition.

there is no more fuse box in this car. it was melted and removed a long time ago. everything is switched via a switch box where the ash tray used to be. the 12V switch that powered the 12V to the MSD box also sent 12V to the little WHITE wire on the top of the alt.

the alt got REALLY REALLY HOT, HOT enough to blister my fingers real bad. i guess its totally shot out. it was not charging crap even before it died. it was also whining.

when i put my other alternator into the car, i will be wiring the white wire to switched 12V, red wire to back of alt, and heavy guage red wire to battery. sound ok to get me around for a while?

edit: and whats the difference between tieing the WHITE wire to the back and switching the RED wire, and tieing the RED wire to the back and switching the WHITE wire?

 

The red and white wires must be on a switched line otherwise damage to the regulator can occurr. You can tie the red(not the rear one, the plug one) to any switched 12 source you want as long as it has the same current capability as the original wireing scheme. The red at the plug must be able to supply full field current for the alt.

 

On my '84 the red wire from the plug is tied directly to the output of the alternator (non switched 12 volt source), and the brown wire from the plug is used to control the field power from a switched 12 volt source.

 

Tim, the reason they recommend sense and regulator supply be switched is this. With the red wire always hot the regulator hybrid IC always has power. The sense wire if switched should keep the pass transistor in the IC in a non conduction mode. It is simply a good idea to have the regulator IC completely off during non use time. Also, if the internal field control pass transistor got leaky it could create a slow battery drain condition along with damage to the rotor and brushes.

 

Makes sense.....

 

Heeeeeeeeeeeeeeelp!

I have an 87 350 TPI Formula. I am going crazy with the damn alternator. Just dropped in a new motor so it hasnt been driven much, still pissed though. Anyway I brought the damn alternator to checkerauto and they say it charges fine, I saw it do so. The alternator is new anway.

I have been digging through these posts for awhile now and this is what I know.

Keyoff
Lug: 12v
s: 12v
f: 0v
l: 0v


Keyon
Lug: 12v
s: 12v
f: 12v
l: 0v

This is what I have been looking at. I cant find the damn bulb either.

 

Posting, oops.

 

What book are you posting these diagrams from?

I need that book!!

 

They are from a shop manual. An '85 shop manual is on line @
http://www.geocities.com/vtcamaro/Wire-Diagrams.html

 

Sorry to beat a dead horse here but I'm having the infamous overcharge problem after warmup. From what I can tell, am I correct in the assumption that the sense wire is running to the starter and then back to the batt? Can I jumper the sense wire on the alt straight to the batt with a resistor wire or inline resistor to make it charge correctly? I just replaced the starter and don't really feel like pulling that thing right now to replace all the wires and fusibles down there.

Btw: Alt tested fine, new battery.... When car is cranked the meter on the dash shows about 14 volts and then in a few seconds (with warm engine) it jumps to 18. 18 volts has been confirmed with a voltmeter across the batt terminals at idle. The alt is a 3 wire Si model, reman Delco....

 

The sense wire comes from key on in run 12 volts, eventually everything ties back at the starter junction thru fuse links. Try this test, key in run position engine off measure the voltage with the plug off the alt at the wire side(not the alt) pins. One should read battery, that's the field source the other is the "sense" it should be about a half to 3/4 of a volt lower. What does not make sense is that the alt if the regulator IC is ok should internally back down over 15 volts. Some models actually use a charge bulb to develop the drop needed for the sense line, guage models do it a little differently. You can take the sense wire and for testing tie it to 12 volts, if the alt backs down you have nailed it down. If everything checks OK and it still does it I would suspect the alt regulator IC. It may be thermally failing and full fielding itself. To read 18v at the battery it has to be putting out over 20 volts unloaded. Keep me posted, very interesting.

 

Hey danno if i measure the voltage at my ECU i get 12.8 volts with the car running!

but if i measure it at the battery or alt i get 14.5 volts

what the heck is going on now?

 

Danno, will test it this evening as you describe after I get off of work... as long as I have enough juice in the battery. It drained the other day from a bad switch in the door that let my dome light on

Thanks for the input.

 

I don't think I'm even going to have to do the test as I was thinking about it on the way to work today. I had already jumpered the sense wire to the alt output with the same problem. When the engine warms up the volts jump to 18+. Shutting off the engine and re-cranking it will let them sit at about 14 - 15 for about 5 seconds then they skyrocket again. As you pointed out Danno it sounds like a bad IC in the alt that when it heats up it indeed full fields the alt. I will run it down to a local alt place and have them check it out this week.

Thanks!

 

Voltage drop in the wiring. My 89 uses a pigtail from the positive battery terminal with a single pin weatherpack connector used to feed the ECM and for a handy way to clear codes without losing radio memory, maybe there is some resistance in it. Best way would be to disconnect the battery and measure with a digital ohmmeter the resistance from the battery terminal to the voltage input to the ECM, then start cleaning connectors. If you are not having a problem I personally would not worry about it since the important stuff in the ECM is regulated down anyway, 5 and 9 volts(I think they also use a 9 volt) but I can't remember. 1.7 volt drop is more than I think is normal but I actually have never checked mine. There is always voltage drop in the wiring simply from length and condition of any connectors-it's something I will look into on mine when I get the time.