Alternator not charging after 3g

[mob]

Hey guys, I installed my alternator with all the wires set to jrichkers diagram. Spliced small white/black wire for stator wire, plugged in small connecter, and used a 125amp fuse. Also got a 4g ground going from engine to chassis.

I had a little miss hap when I connected the battery the positive terminal on the alternator was touching the alternator case, so I got some sparks. I look at the fuse in between the lines and it "looks" alright. Its one of these fuses, can you tell if there good just by looking at it?

Im not sure what else it could be. The gauge isnt all the way at the bottom its at the bottom quarter of the gauge, and it has no response when I hit the gas, it used to be at the middle or top quarter with my old alternator, and when I hit the gas it would go up.

Any ideas?

 

[mob]

Well I found this info from HISSIN50 while searching i guess ill pick up a much needed muiltimeter from work today and test all this.

Chances are that the alternator or alt wiring is the issue - I've not seen a battery cause an issue like that (which is not to say others have seen it).

When it goes to crap, put your meter (set to the 20 amp DC volts scale) on the alternator's charge stud (red lead to the charge stud, black lead to a bolt on the motor). You should see above 12.6 volts with the car idling. Now do the same thing at the battery (with the car idling). If both are the same or very close, and under 12.6 volts, chances are that you're running off the battery.

At that point, I would check the wire JR mentioned. See if it shows 12 volts. If not, you found the (or one) issue.

If you find that you have decent voltage at the alternator but not at the battery, go along your 4 AWG cable and check it at the connections (e.g., for my set-up, I'd check each terminal at my ANL fuse and the connection at the starter solenoid's battery lug). A bad connection would allow the alternator to put out but the current would not reach the battery.

The IR comment was just a reference to a loose or bad (Dirty, etc) connection acting up when it gets hot (resistance causes heat, heat causes more resistance, and it snowballs).

I'm sure JR will have some eloquent thoughts as well (his posts are a LOT easier to decipher than mine).

 

[87WhiteStang1]

it could be that the fuse is blown. it could be a few other things too. make sure your belt is very tight and not slipping at all. you may want to take a look at the ignitions switch because if it is burnt up or melted on part of it it might not be getting a good enough connection on one wire.. there is one wire on there, i forget which one, but it has something to do with telling the alternator when to turn on.

 

[HISSIN50]

If you have a test light, you can check for battery voltage on each lug of the fuse.

If you have the fuse on a bench, and you have a DMM, you can check continuity between both halves of the wafer.

On your fuse, maybe you can see the fuse element if you remove the fuse and look at the back side of it. The elements generally look like a Z (or N, depending upon how you hold the fuse).

FYI, if you have a Harbor Freight near you, they often have DMM's on sale for under 5 bucks. They work just fine (I've been using them as throw-away meters for years).

Good luck bud.

 

[1990Coupe]

is an alt from a 94-95 sn95 v6/v8 the same as a 3g? Really noob question coming from me i know..

I was under the impression they are much better then fox alt's.. if thats the case would i have to do the 3g upgrade or can i "plug and play"

Sorry mob for teh steal

 

[mob]

Yes the 94/95 alternators are 3g 130 amp better than the fox 2g alt's. If you are going to a 3g it wont be a "plug and play" youll have to splice some wires and everyone recommends upgrading from the stock 10 gauge power wires to a fused 4gauge so you arent driving around with a potential fire hazard.

Thanks guys I'll be looking at all this today.

 

[mob]

Alright I got 12v at the battery, I had about 11.94v at the solenoid, and I had like 12.4v at the green wire on the alternator. Now when I put it on the alternator weird things happened. It wouldnt get a straight reading. It would go from like 3v to 8v to 19 and 18 volts and stay around there then sometimes it would show 1_.__v it wouldnt show an numbers after the one. I tested both terminals on the fuse and both sides were at 0v not even .01. This is all with the car on. I took off the fuse to inspect it but it looked completley normal, just like in that picture, I didnt see any z or N pattern on the back of it, it was flat. What are you guys thinking? Fuse or alternator?

 

[HISSIN50]

One side of the fuse should have shown battery voltage even if the fuse was blown.

Be sure the battery in the meter is good.

With the car off: Test the battery again. Then move the positive meter lead to the alt and test the charge stud like you tested the battery. The readings should be the same. If there's a meaningful difference, tell us what it is. If there's no difference, the fuse should be ok.

If there was no difference, test both again with the car running. Something might have been not connected decently with the meter. Set it to the 20 DCV scale.

 

[mob]

Thanks for the help hissin. I really dont know what it is, I put my old alternator back on because I really dont have a couple days to troubleshoot this. The meter is brand new I just got it yesterday. I find the meters hard to read sometimes but I put it in the V section at 20. Could burning the tips of the wires have an impact on the connection? To get the ring terminals crimped I had to heat the crap out of the terminal till it was purple and crimp it down. Im sure the ends of the wires got real hot, doubt that has an effect on it though. I am going to get the alternator tested just incase, then go from there.

 

[HISSIN50]

If you got those weird readings at the alternator while the car was off, chances are it was just a bad test (something was wrong with how the probes were touching the terminals).

The heat should not have hurt the wire. I had to cut and modify my terminals too (I cut a chunk out of the top of the circle, closed the ring, and then reconnected the ends).

Testing the alt sounds good. A short could have fried part of the reg circuit or a diode. The fact that your 2G works means the regulator wiring itself should be fine.

 

[mob]

Yea I made sure that my 2g worked and it works fine so all the stock wiring is ok. I checked the alternator today on a bench tester at my work and it was putting out 12volts.

I got those weird readings while the car was running. It seems like something is wrong with the power wire because I have 12v every except the wire itself. Is there a special way to put the test leads on it? I just touched the tip of it to the wire terminal and to the fuse holder post but got nothing. It doesn't matter if you put the fuse on top of the terminals or terminals on top of the fuse in the fuse holder right? Im trying to think of anything I can haha.

Is there anyway I can check just the fuse without hooking it all up? You said check to see if it has continuity with a DMM, how do I check for that?

 

[Saleen0679]

Is there anyway I can check just the fuse without hooking it all up? You said check to see if it has continuity with a DMM, how do I check for that?

If the power cable is disconnected or you pulled the fuse (you don't want power going through a circuit when you're measuring resistance) set the meter to one of the Ω scales and measure across the fuse. If the fuse is good the meter should read zero (or pretty darn close). If the fuse is blown the meter will read 'OL' or give some type of 'open' indication.

 

[mob]

Awesome info, thank you very much.

 

[mob]

I checked the resistance on it on the 20k setting. I put both leads on the same side right? When I did that and moved it around it stayed around .00 sometimes when I moved the lead around a little fast it jumped up to like .33 at the most, but on both sides it was a .00 for the most part.

 

[HISSIN50]

I checked the resistance on it on the 20k setting. I put both leads on the same side right? When I did that and moved it around it stayed around .00 sometimes when I moved the lead around a little fast it jumped up to like .33 at the most, but on both sides it was a .00 for the most part.

You'd put one lead on one side and one lead on the other side (by side, we mean laterally, like an east and west side of a bridge) of the fuse element. If the fuse blew, the two sides are no longer 'connected.'

 

[mob]

Oh I got ya, I think I did that and I got that 1_.__ reading. I am guessing thats the same as the OL or Open? I will check it again real quick to make sure

EDIT: Yea I just checked it again, and when I turn the DMM on and put it on the resistance setting, and have the two leads in the air it shows that reading of 1_.__, and them being in the air would be an open circuit cause there not touching anything right? When I put one lead on each side nothing changes it stays at 1_.__, I am going to order a new fuse from NAPA today glad I didnt blow anything else. Thanks guys. Hopefully this is it.

 

[HISSIN50]

I think you got it.


All meters are different. Mine shows an I (Infinite) for an open, for instance.


You can get fuses pretty cheap online (for when it comes time to order spares). I keep at least one spare in the glovebox.

 

[mob]

Yea I was thinking about getting a spare but NAPA down the street carries them in stock now so it wouldnt take more than an afternoon to swap it out if needed, lets hope I dont blow it up again haha.

I appreciate the help fellas, thanks.