I'm working on my '86 305tpi iroc. I tested the alternator 3 times.. it passed all test. I checked the fuses... none blown. I'm getting 12 volts to the little red wire on the plug and 19(?) on the little brown wire when I turn on the key.
But when I start the car the alternator is not charging(not coming on).
Okay... So, is the 19volts at the brown wire what I'm susposed to be getting with the key on? Also I don't see a dummy light on my dash when I turn the key on(is there a light since i have the cluster amp gauge?).
I did notice that my headlight switsh is bad(I have to push up on it to turn on my dashlights). Will this cause problems with my alternator turn-on circuit?
Also I just recently swapped out my steering column with another identical one. Would the key switch cause this? (The key cylinder seems to be in great shape.)
And if I read it right... I can jumper a keyed 12volt source to the brown wire to activate the alt right?
Sorry for all the questions... I'm trying to fix a hack job the right way. Some people should never work on cars.....

 

Okay... I did some more searching. I don't have a charge idicator bulb since i got the gauge. But it still runs through the fan fuse right? My alternator has a plug with 2 wires only. Most of the post I searched have three wire plugs. So Am I susposed tp be getting 19volts from the brown wire with ignition on? That seems high to me. Or maybe I'm reading it wrong. But if I jumper a wire from the battery to the brown wire it. Will it activate my altenator? I can run a new wire to the fuse box. My wiring has been pretty hacked up....

 

OK, let's keep it simple!

You can order a factory wiring diagram which will be in a factory service manual set. This will tell you the correct way things should be wired.

Also go to a wrecking yard and/or look at another car of the same model to see how everything is wired.

Then with a voltmeter, turn the ignition switch to on (without starting) and you should read 12 something volts at the battery. So you are placing a load on the battery and it should have enough power to stay at 12 something volts.

If the battery is below this, charge it with a battery charger.

Then once you are reading 12 something volts with the ignition on, start it and you should now read 13/14 volts on the battery. This is the alternator kicking in and charging the battery.

If it is still reading 12 something volts after starting, then there is a problem with the charging system.

There would be detailed troubleshooting instructions in the factory service manual for your year/model vehicle for this and all other problems. And best of all, it is for your specific vehicle! So everything in the books pertains to everything in your specific vehicle. You can order a factory service manual set at your dealer or here...
http://www.helminc.com

Note if you charge the battery and it still drops below 12 something volts with just the ignition on, then you have a bad battery - it is not holding its charge.

 

I can charge the battery up and it will hold a charge. But I'm not getting any voltage from the altenator. I'll call up my buddy that works at the dealership and get the print-offs of the wiring schematics.
If I were to install a one wire alt. Would my amp gauge still work? I read somewhere that it doesn't read from the alt directly. Is that right?

 

I would keep everything factory. Factory alternator and factory amp gauge if that is what you have, then wiring factory. Then you have the factory wiring diagrams for how everything should be connected (keep it simple).

If it is an add-on amp gauge, stay with the factory alternator for now and maybe disconnect the amperage gauge. Get the vehicle working first.

Then get a wiring diagram for the amp gauge and connect that later.

If you do just one thing at a time, then you can see the results of what you did. If you connect the amp gauge later and things stop working, you can reverse what you did and return to a working vehicle.

 

i had the same problem with my alternator, i have an 86 iroc tpi 305. now the problem i had was that the battery went dead because the alternator, so i replaced it, then when i had a short circuit checked out at a shop they said the alternator was bad. knowing that they were some jive bastards, i took it to my high school shop teacher where we hooked up a multimeter and saw that those 2 wires that come off the alternator looked good, but if you gave them a wiggle it would cause the voltage to just to 15 or 16 with the car on. and when i stopped wiggling it it would drop to 12.

how did u check the alternator? use a voltmeter, negative probe on the battery post and positive on the little bolt where the thick wires comes out from the alternator. it should be like 13 or 14, and also try to wiggle those other 2 wires to see if the voltage changes.

if you had kragen or autozone or some of those guys check your alternator with it off the car, i wouldnt trust their machines very much.

 

It might be your alt. 2 wire alt, 3 wire alt? Double check to make sure you have the right one! Good luck.....

 

This sounds very high for alternator Voltage. If you were reading your voltmeter correctly and it was working properly then your 18 or 19 Volts should indicate a bad regulator in the alternator only. Recheck the circuit at the alternator wires and battery with another meter. Then replace your alternator. I found mine for $65 refurb from Pep Boys. It works fine at 14.3 Volts.

 

(Billy_Bob) Yea the car is all factory So I'll have to get the schmatics on it today. I was pretty sure it was charging before I switch the steering column out. But it might've been that the battery was fullly charged then and I didn't see the gauge drop.
(gurkgurkgurk) I had the alt tested and o'rielly's and advancedautoparts. I took the alt off and took it in. I don't drive the car... I'm trying to fix all the little bugs first. It held 15volts under the load test and passed all the other test the machine runs.
(y84pauloflondon) The alt is a 2-wire plug and m car has a 2-wire plug
(TA-rocks) The 19 volts I was testing was from the small brown wire going into the alt from the plug. I believe that it's the exciter wire... So I must've read it wrong. I don't know how I'd get 19volts when the battery is sitting at 11.58volts. I'll worrk on it some more today and see what I can find. Thanks guys.

 

I agree. 19v is high. Alternator should be in the 14v range. If you are strapped for cash, you can just try replacing the regulator for around $15. Its inside the alternator, but not to tough to replace. Or replace the whole alternator if you have the means. Autozone and Kragen can test the alternator off the car. You want to eliminate the alternator/regulator as the problem before you get to involved in the potential wiring issues.

 

Hey guys (dstss,TA-ROCKS,gurkgurkgurk,Billy_Bob) could he be arcing out some where? Could he have a bad wire thats grounding out? (like a bad spark plug wire)!!!!! Like gurkgurkgurk said check the wire connections, give'em a wiggle, and check there condiction from one end to the other end, make sure their aren't any cracks in the rubber/plastic.! I also agree with dstss, it could very well be your regulator. If your Canadian, canadian tire and part source should be able to test your alt for free......

 

There is a relay under the dash that powers that brown wire. Its in the same area as that god forsaken door buzzer. should be near the center console. Check that. Pull the relay and check the voltage at the brown wire. If you have anything with the relay out then you have a short somewhwhere.

 

Okay I'm a day behind. I got to lookin at the car again. Battery test at 12.28v, I'm getting 11.96v out of my little red wire on my plug into the alt, 12.28v from the big wire bolted to the back of the alt, and nothing from the brown wire in the plug(with key off). Now if I turn the key on I get .79v from the brown(which is nothing), and then it causes my little red wire in my plug to change to .979v Also my car is not starting now. But it I unplug the connector and test my little red wire I get my 12v again. But still nothing from my brown.
I just saw the post about the relay and I'm going to check for that now. Does this sound like a short from the key switch? I don't recall having problems until after I switched out my steering column. I'm also going to put my old key cylinder in this column to eliminate it being the culprit.
And I know the alt is good It's been tested 3 TIMES and passed everytime. The only things I can think of is... the key switch(because I changed the complete steering column with a used one)... a short (maybe I bumped a wire installing the column), or my starter fuselink( my starter has been sounding awful lately and I think it might've feedback through the fuselink and weakend it.)
Anyone have anygood links to find out how to test for shorts or fusible links? I usually check to see if there's continuity for a short to ground. But is there a way for a short to another HOT wire? And fusible links... Can you just OHM them or do you have to have a powered voltmeter tester to test them?
Thanks for the other tips guys. I'm really hoping to get these bugs worked out. I thought I almost had the car to where I could start driving it. And of course this started up...

 

A fusible link would be just like testing a piece of wire or a fuse. Although you should disconnect one end of the wire for testing.

How to test fuses...
http://www.dinosaurelectronics.com/Test_Fuse.htm

 

Well... I think I found my problem. I was going to take the battery out and the starter off and get them both tested. Also I was going to un-hook the starter anyways to start checking the wires and links. Well... I got under there and the main stud on the solenoid for the battery cables and stuff was loose. I don't mean just the nut... The WHOLE THING! I'd say this is where my problem is at. Now I got to figure out how in the heck to get the starter off! My Chilton manual just says to unbolt and pull it down in between the y-pipe and the frame. But there's now way it's going thru there! My pipe is bent or something. I'm going to try and take the trans lines off and pull it thru the back. I'm trying not to pull the exhaust off because I know I'll break one of the y-pipe flange bolts. And I can't afford header right now. Anyone else had a pain getting there starter off?

 

connections, connections, connections.... its always the little things that bit you on the a**. If this works, congrats As for the starter, No never have, thank god...... good luck!

 

Okay, update time... I got the starter switched out. After an hour of searching I found it to be very helpfull to take the solenoid off. But my car is still not charging.
I know I had the alt tested at 2 different places 3 different times. But I'm pretty sure it's the culprit. Help me find out if I'm right....
If I start up the car, and unplug the 2-wire connector. I get my battery voltage out of the little red, and I get my battery voltage from my little brown wire(at the connector. I shut the car off. My 12v shuts off to the brown wire. (Which is the way it should be.) If I start the car up and plug it in My brown wire goes crazy. I was reading 19v last weekend now I'm reading 4v. I still get my battery voltage out of my red wires.
I think my regulator is shot. What do you guys think?

 

i had the same problem. alternator "tested" good at kragen but the voltage at the wire wasnt good. and i had charging problems. brand new alternator fixed that. dont trust those machines kragen or autozone uses to check alternators, they dont accurately simulate on car conditions. unless of course they checked the alternator while on the car.

 

I don't know if your on a budget, but a new or even a refo. alt should be fairly cheap. Well at least compared to us CDN. And others have already mentioned the regulator before.....I was going to test my 87 GTA for you, and get num for you, but my alt has 3 wires, 1 red, 1 brown, 1 brown/white..... I don't know how I can help you from here on... sorry

 

Is that alt that your testing/using, did it come with the car when you bought it? Did you buy it new after? The reason I ask is cause I took another look at your pic of your noodle soup under the hood (wiring hack job) sorry man, I feel for you!!!! Is there a Chance that the hacker removed, relocated or cut the third wire, Even the alt clip looks spotty.....? I find it odd that your 86 is 2 wire and my 87 is 3 wire. Try going to a good parts store JUST to look at a NEW alt for your car, to see if there's ANY differences.... I got a feeling that maybe it should have three wires, MAYBE....("a shot in the dark is better then no shot at all)...Good luck.

 

The regulator is inside the alternator. If it was bench tested, a bad regulator should have shown up on the test. But anything is possible. I have seen parts pass test only to have the replacement fix the problem. Why? Who knows. Regulator is about 15 bucks and worth a shot. Also you can replace the wire connector that plugs in to the alternator for $2-3. Might want to eliminate those. Next possibility is a short somewhere. Check both ends of each possible wire while moving them around to see if you have a partial break in a wire.
Also try to avoid plugging or unpluging in wires while the motor is running. There is a small possiblity of creating an electrical pulse which can burn out other electrical parts including your ignition module.

 

Try this, Clip the brown wire and run a test wire from the + battery post. With the car running connect the new wire to the alternators brown wire. Check the voltage at the battery. See if it increases or stays the same or goes crazy like before. This will verify the circuit the brown wire is attached to. It honestly sounds like your alt is shot. I had 2 alternators test "good" at auto zone but they were only putting out 12.4 volts. Autozone calls anything above 12 volts "good".

 

I did unplug the connector and only put the red wire back in the plug and ran a jumper wire to replace the brown. When I hook up my jumper wire to the battery it still doesn't charge and my alt starts to make a noise and smells funny. I still think it's the regulator or the alt itself. But I gotta wait until tomorrow to get another alt.

 

hi , i have a similar problem ,,my car starts fine and runs fine ,,the alternator charges according to my multi-meter at 14.6 volts,,but if i put on the lights wipers and fan etc ,,the car almost wants to shut down and die, if i turn all off it idles great again.. ,,it this because the alternator cannot produce enough charge volts/amps under load?..if yes i will get a new one ,,but one quetion ,,i have an alternator with the small plastic plug at the top ,,there is only one wire plugged in there..is this for the gauge?.. there is one larger wire behind it , this goes to the battery..where should the other wire go at the plug go ,,or is it not necessary??..thankyou ,any help is apreciated..

 

That single wire should be there and hooked up. I can't tell you what it does. But my 92' silverado has that style alternator on it.
As for your problem... Always start with the connections. Check and clean the battery terminals, check for loose wires at the starter and battery, and get your battery tested. It sounds like you might have a bad ground somewhere or a weak battery(when it is under a load).

 

a fully charged battery is 12.6 volts so if you put anything more that that into it u are charging it. In my opinion a alternater should be putting out around 14 volts when running. Where the 2 small wires hook in one of them should be labled "field" or just an "f" this wire induces the field voltage into the alternater to create the magnetic field needed to create voltage. If you cant find where u are loosing this power you can take the wire for the "field" and jump it to the big red wire on the back and this will make it charge if its any good. If that works for you and you don't mind rigging your ride then you can hook that up to a key on power wire in your car or look at the wiring diagram in the service manual and find where you are loosing this "field signal"

 

Well... I fixed my charging problem. I installed a one wire alternator from Summit racing today. I'm running 14.45volts at idle. It was cheaper to replace my alt this way. A reman form advanced(etc) was going to be around $100 for a lifetime warranty. I got this one for around $80 from summit and it's a 100amp.