StealthElephant

I did an engine swap, and my alternator is overcharging the battery. The voltage regulator doesn't seem to be working.

The alternator has a plug on one side that goes to the battery and the other side has a connector that runs into the firewall. I'm guessing since I have a carbed setup now that the computer isn't doing something anymore, and the voltage isn't being regulated. Someone told me I have to run a diode or something.

Any help would be appreciated, I don't want my battery to explode on me.

Maverick H1L

iTrader: (8)

The ECM don't care how much voltage the alt is putting out unless it is TOO much voltage and then the ECM gets fried .
You need to get a NEW or REMAN alt because ours are NOT servicable, believe me, I've tried to replace the relay in my old one and ended up trading it in on a new one. Advance usually carries Palladium reman alt's for around $65 with the trade-in of the old one. MAKE SURE THEY BENCH TEST IT IN FRONT OF YOU FIRST BEFORE YOU PAY!! Several people on here have had problems with these remanned alternators and have gone through two or three before they got a working one.

StealthElephant

So if I get a new alternator it will regulate itself w/o problems, w/o any help from my computer(Which is disconected).


Thnx

Maverick H1L

iTrader: (8)

Yes. Most alternators produced by GM since the mid '70s and just about all of them produced in the '80s have internal voltage regulators and will produce around 14 VDC regulated. The ECM, like I said before, has nothing to do with the alternator other than to receive power from the charging battery.

Also, you can go to a junkyard and pick up a used pre-1987 alternator from one of our cars. GM switched to non-serviceable units in 1987. It is a lot cheaper to buy parts for one than to buy a whole one, so I think that would be something to look for.

StealthElephant

Well this is a reman alterantor, I had it put in like 8 months ago when the one before it went out. All I know is that the current one has 2 connectors, 1 on each side.

So the internal voltage regulator has nothing to do with ANY of the wiring? When you connect the alt to the positive lead of the battery it should not only charge, but read the current battery voltage?

Thnx, I think I'll go to pep boys and just pick up an alternator.

Maverick H1L

iTrader: (8)

The way I understand how the alternator works is that the ring terminal going straight to the battery is for charging the battery ONLY. The other connector has three wires and goes to the rectifier pack inside the alt that reads the battery voltage and power usage and adjusts the alternator output accordingly.

Also, I have heard that having a defective alternator kills the battery, and having a dead battery kills the alternator. Check both.

StealthElephant

So the alt reads the battery voltage from itself? The 1 wire that goes to the battery is the charge line, but the alt must be reading the battery voltage with that line as well right?

Maverick H1L

iTrader: (8)

It is in a feedback circuit. The alternator rectifier pack receives voltage readings from the starter solenoid through the RED wire, which constantly receives power from the B+ terminal on the battery. The rectifier pack takes these readings, measures the current drop in the battery from accessories and the engine, and turns the alternator charging circuit on and off as needed. The ring terminal that connects to the battery delivers the charge TO the battery and therefore is a heavier gauge wire. One of the three wires in the weatherpack connector is also for the charging indicator/gauge, and tells if the system is at a dangerously low voltage or not, and the last wire in that connector, the other not-red one, is for the "charging fuse" I guess you could call it. Unless I am wrong in this and someone can help explain it better.

Think about it. Would you deliver voltage to the battery with an 18 gauge wire, especially if that voltage contains a 105 amp current? I didn't think so... The smaller wires in the weatherpack connector are what tells the alternator rectifier what voltage the battery is at and then the alt decides to charge based on that red wire.

The only things in the driver's area that have to do with the ECM are the SES idiot light, the ignition switch and lock, and the tachometer if your car has one. The rest is all controlled by separate switches/senders attached to the engine itself (coolant temperature sensor), or by switches controlled by the driver (such as headlights).

Danno

Let me clear up some misinformation here. Your 87 uses most likely the Si alt. It should have the output lead going to the battery on the rear and 2 wires in the top plug. Usually the plug wires are 2 different sizes guage wise, the heavier of the 2 is the field supply the lighter one is the alt "sense" lead. The later CS unit is basically the same wiring wise. First, what is the charging voltage? Most GM regulators have the setpoint voltage at around 14.8 volts. The plug wires, one will have 12 volts on it all the time the other sense is the one that turns the alt off and on. If the sense wire is tied to 12 volts battery feed the alt will charge at low output for only a short time. The sense wire may be a resistance wire or go through a lamp if so equipped but it is usually a half a volt or so below battery voltage to keep the alt ramped up with high load. The rectifer pack has nothing to do with measuring any voltage, it converts the AC voltage developed by the rotation of the rotor and induced into the stator, which is controlled by the regulator field voltage which is controlled by the IC inside the alt. The rectifier converts the mulitphase AC voltage to DC to be used by the vehicle. You need to measure first the battery voltage when its running, on a cold start it may be as high as 15 volts then slowly settle down to an average of 13.5-14.5 volts. Next measure the voltage at the 2 plug wires with it running. One should read exactly battery voltage, the other may be slightly lower. If everything is OK most likely the regulator IC in the alt is bad. On any IC controlled alt never remove any wire with the battery connected. The IC can be damaged, especially on the newer CS and CS"D" models. Incidentallly, all the GM alts are serviceable. I fix them all the time, but unless you have the right tools in many cases it's not practical.

Maverick H1L

iTrader: (8)

My 87 has the CS alternator, and I tell you it is NOT servicable. If it is, then tell me exactly HOW ARE YOU SUPPOSED TO REPLACE THE DIODE in them things? It can't be done!

Danno

Are you joking? Try www.alternatorparts.com they offer the lay person a full diagram and replacement parts. You have to, first unsolder the stator, then crack open the case(again you might need to make up a tool, I did with the help of my neighbor who is a machinist) and once the case is open you have access to the brush holder, rectifier block and regulator IC. If you order the "iceberg" kit it comes with full instructions. When you unsolder the stator- that is actually attached to the rectifier package which then is held by male TORX fasteners. Who do you think rebuilds them anyway? 86/87 was the year they went from the Si to the CS series, depends on manufacturing date. This so called"can't be done generator" is serviced every day, even by many guy's here on TG. I just got done doing one this afternoon. Never say never my friend, just do the research. They say the same thing about the "D" version, guess what it's a bigger piece of cake than the 130. By the way, to whom it concerns GM now refers to all alternators as now officially generators. Talk about retro.

Maverick H1L

iTrader: (8)

Okay, you win. I give up. But I kind of needed a new alternator anyways (bad casing due to metal fatigue) if I had that info before, I probably wouldn't be needing a new alternator bracket right now because the alternator took the bracket with it, or just part of it anyways!

Danno

Nothing to win or lose here Mav, having 4 GM cars and another on the way for me it's a matter of economics. Also, I live in a small neighborhood full of motorheads. I had this house built 8yrs ago and the day I moved in they didn't all swarm to welcome me, they were over checking out the IROC. They all have kids who are motorheads as well, there is not a day goes by someone is standing in the garage with some electrical gadget that needs repair. I will NOT use any aftermarket parts anymore, so it's either dealer or fix it. Even with a parts account with the local chevy dealer a GM reman generator is $200. I would agree that a one time deal may not be worth the aggravation, there are a few tricks you learn after you do a few. I corrected that web address to link to if you are interested.

Maverick H1L

iTrader: (8)

Well, for me it was either reman or nothing... the casing was broke (right at the pass-through bolt housing for the bracketry) plus the diode was shorting out the battery. If I could have afforded GM I would have gotten it... even if I had to rebuild it myself from a junkyard...

StealthElephant

Well as you said, my 87' alt has the positive lead and a connector that joins with the starter harness. It disappears but I'm assuming your description is 100% on point.

Basically, with just the positive lead and no connector, the alt does not charge, if you plug the connector back in, the alt charges like 16 volts nonstop. Even if I turn on very power accessor (hibeams, radio, defroster etc etc) my volt meter is reading like 16. I had a voltmeter on on the battery as the car was running and it was like 17.16.

What is the IC? I'm guessing that my voltage regulator is blown, because the only way an alt goes bad is it doesn't charge at all, or overcharges right? Or could I have a wiring problem?

StealthElephant

Sorry about the terrible quality, thats the connector on my alt.

My buddy who has an 86 monty gave me one of his old ones, it has 2 metal prongs, it isn't the same as mine. Mine has a black slot, the connector that goes in has 3 prongs.

It says Delco-Remy, what kind of alt do I have?

I went to pep boys and asked for an alt for an 87 camaro. They have the same on that is in my car, but they wanted 120$ WITH a core, I wasnt paying that much. Will one of those iceberg kits work for me?

Can I be sure its the alternator that is the problem and not a wiring issue? As far as I know, the stock starter harness wasn't touched. The starter harness (which had the alt/starter/etc) was separate from the fuel injection. I don't know though, the alt worked fine before the engine swap, we had electrical problems (fuel pump was turning off when i hit the brakes, gauges would turn off when i hit the brakes, everything was all messed up) So we finally fixed all my gauges and power supply, and the alt wouldn't run. Guy who was helping me cut a wire in the fuse box, he reconnected it and the alt started charging again. Though it's been overcharging ever since, but it worked fine before the engine swap. I don't want to buy another alt, and find out its the wiring thats the problem not the alt, then be stuck with an extra alt i don't need.

The alt is simply putting out 16V+ all the time, nonstop, so it has to be the regulator? There is no wiring to mess up that would cause this condition?

thnx for all the info guys.

Heh, I just noticed that, I am 99.9% sure I do have the CS-130, the picture on altparts.com looks exactly like mine, down to the connector. I am guessing during my engine swap, that the connector on my alt was taken on and off several times with the battery connected. That is probably why it hasnt regulated since I put it back in.

I'm glad I took the time to read all this, I just learned a good deal about alternators.

Danno

All the generators are Delco Remy, except the newer ones or "D" units that say Delphi Automotive Systems on the front. Like I said 86/87 was the changeover date the monte probably has the Si, you have the CS 130. Autozone tests them for free, or in lieu of that try a local alt/starter repair shop. A cup of coffee and a bag of doughnuts and I struck up a relationship with a local rebuilder who now sell me parts cheaper than online. Just ask him to spin it up, may only cost a few bucks. The "Iceberg" kit does not come with the regulator, you have to order it separately. What you describe is called "full fielding", normally the reg IC is the culprit. The Si units had a hole in the back you could put a screwdriver in and full field it, the CS units don't. PM me if you want after it's tested and give you the up's and down's of tackling it yourself. I converted my 89 to a "D" version, the article is posted. What a vast improvement over the straight 130. No more bouncing tach with the turn signals with high load, and the old one was a 140 amp unit.

Mikes86SC

Another possibility for an overcharging alternator:

The butt connector, does it have 1 or 2 wires? My 86 LB9 has 2. One to the dash gauge, the other to the starter. The one to the starter is the feedback, which tells the alt the battery voltage. That wire has a fusible link by the starter. If that link is blown the alt may see no voltage there, so it will put out mak power to charge the battery.

StealthElephant

I just talked to the guy who did the swap with me, he thinks that the problem is some kind of diode/resistor (or the fusible link you just mentioned) that is causing my problem. He said the fact that the alt STOPS charging when i disc. the connector plug means the regulator IS working.

Fire"Dutch"Bird

iTrader: (1)

The Iceberg kit is a MUST for the 130 A alternators, mainly because of the cooling fins at the backside of the housing (those high output alt. get realy hot...!!)

Danno

The reason it stops charging when the plug is removed is because you are removing the field voltage to the rotor, 130 alts get thier field voltage externally like the older delco units. The heavier wire, usually red is the constant 12 volts for the field. The tan or brown wire, usually a smaller guage wire is the sense/turn on voltage, it is key controlled. The red should read battery voltage the tan should read half a volt or so lower. The one to be concerned with is the tan sense wire, if it is hooked up OK then the alt is bad. I am slightly confused, is it the stock alt or the one that came with the engine swap?

StealthElephant

Stock alt from my 87' 305 TPI. Ill uncover my wiring and check the wires for the correct voltage. Thnx

PS: Should the car be running while I check voltage?

Danno

Pull the plug and test with key on engine off.

freebird1980

Hello Everyone.. Here is my problem- I have a 87 z28 camaro. I have 2 alternators that 3 different parts stores checked as good but my charging gauge in my dash shows 10 amps. I checked the output at the alternator it shows 11.4 amps. When you remove the + battery post off the battery with the car running, the car shuts off. It happens with either altenator on the car and with 2 different new batteries. Is there a in-line fuse or something that will cause the alternator not to charge? I have an after market volt gauge in my dash that reads 10 volts. My factory gauge in the dash reads 8 volts. Thanks.

NINĊ

freebird1980

Hey, I found the non-charging problem with my 87 z28. I started looking in the wiring harness and found a bad wire butt connector about 6 inches up in the harness. I cut it out and now my z runs and is charges just fine. Thanks for the advice.

freebird1980

1987 z28 not charging again- checked battery-12.7 volts without engine running- checked alternator with car sitting running-14.5 volts- turn lights on or turn anything on and alternator gauge shows 11.5 volts- checked wiring harness from alternator to firewall of car-found nothing wrong- what now??

NINĊ

aaronp91

i have a 85 firebird v6 2.8.. My battery was not charging so i replaced the battery and the alternator.. Battery still not charging the alternator has power going to it. i was told to check the cluster (dash) and see if the battery light came on.. it doesnt so i replaced all the light bulbs n the back of the cluster... Still no battery light... So what should i replace next? the little green housing the lights go n? Were can i get them? and which light excatly is the battery light? i was told wit that light not working that the alternator will jus run full speed causing it to heat up very fast and pop belt after belt. Which is what it is doing!! PLZZZ HELP ME!!! you can e mail me at aaronpost91@yahoo.com or call me or text me at 843 364 2548... i need to fix this asap ty so much

aaronp91

On the 85 firebird i have found that the alternator is charging but its over charging and overheating very quickly... what could be causing this?