Geo Tracker alternator problem

old

Well-known Member
I'll start off by saying if you cannot be nice and act like a bully please hit the back button NOW.

So I have change the alternator twice now. Both bench test good. The alternator is much like the common Delco 10SI wit h3 wires. All 3 wires show battery voltage on them when the key is turned on. The bog charge wire has an 80amp fuse in line which is good. The black and white wire has 12 volts on it with key on the other small wire has 12 volts. All fuses have been checked and are good. Idiot light works. But the alternators are not charging at all. Not running battery voltage checks good after charging the battery. Start it up and battery reads 12.5 give or take a little bit. At this point not sure what the heck is wrong. I know the alternator has a good ground. So what am I missing??
Thanks
 
Start it up, check the voltage coming off the big output post. Check directly from the post to the alt case, see if it shows the normal charging voltage.

If so, there is a weak connection between the alternator and the battery.

Where you been hiding?
 
The Tracker is sort of GM, so if you have them check the tightness of those damn GM side mount battery terminals. Not too tight, you don't want to strip out the battery.
I have had them bolt "tight" but you could still wiggle the cable end because the bolt was bottomed out.

I have to re tighten mine about every 6-9 months. When they need to be tightened, [u:e3177439a0]it will allow it to start but it will not charge[/u:e3177439a0], then eventually the battery is dead.

Also, with key on but engine not running, is the back end of the alternator shaft area magnetic?. If yes, it is working but not getting to the battery.
 
I was an electronics tec. I worked on computers back when they where the size of a fridge which is a whole lot different then an alternator on a car and not near the same things
 
To be able to do that I would have to hook a wire to that post and then run it up and out some place because with it running you cannot get to the alternator. By the way to check for a good ground I checked it by shorting from the charge poet to the alternator body so I know the wire to the battery and ground are good

As for where I have been I have been here all along but if you read the opening line you might be able to figure out why I have not been posting and Hobo like always just showed he is one of the Y-T bullies
 
This ain't "rocket surgery". What are the voltages on the "excite", voltage sense, and alternator output terminals with the engine running?
 
She has been getting by, by me hooking the charger to it over night and she does fine for a few starts but if she starts it to many time she has to get a jump start. This is the only car we have that she can drive so I need it fixed but so far it has not wanted to work
 
I have not checked to see if the back end of the alternator is magnetic but it is also almost impossible to get to the back end with it installed. Top post battery by the way
 
Only way I can check that with it running would be to hook a wire to it and run it up some place. Cannot get to it when running and can only get to it not running by unhooking the belt and swing it out to the side as far as it can go and even then it is tight
 
I know you said you checked the ground wire, but did you actually take it off where it attaches and clean both surfaces, if you can get to it? Had a tractor a couple of weeks ago that we put a new alternator on and tested the output voltage on. It said it was putting out close to twenty volts when it was only a twelve volt alternator. Didn't want to run it clear to town and get another one. I ended up finally pulling all the wires off the starter and the ground cable and wire brushing them. Put them back on and voltage dropped down to where it was supposed to be. Don't know what was wrong but cleaning worked.
 
(quoted from post at 23:26:29 09/10/18) I have not checked to see if the back end of the alternator is magnetic but it is also almost impossible to get to the back end with it installed. Top post battery by the way

Maybe you can snake an old wire coat hanger in there to get close enough to "feel" it pull?

Did you do the "disconnect battery while running" test to see if it still runs on alternator only?

I know you said you charge the battery overnight so she can get by for the day. Maybe the battery is taking a charge but it is not holding the charge and the daily trip(s) are not enough to recharge like the overnight charge?

You probably have already tried a different battery.
 
Only way I can test any of those would be to cut and splice in wires so I can test when running. The alternator is in and under so much one cannot get to it when it is in place and the belt one and running
 
I know better then to pull a battery cable off while running since that is a good way of letting the smoke out of an alternator plus if done wrong can kill a person.

As for different battery I had not tried that till today and that was how I got her home today.

A couple days ago I did check battery voltage after it had sat a couple hours off the charger and it was around 12.5 plus.
 
Reason I said alternator ground was good was I used a short piece of wire to go from the charge post of the alternator to the alternator case and got the sparks should have when doing that and then double checked the 80amp fuse to make sure it did not blow when I did that
 
friend had a Tracker, it had electrical problems for years, seems about every connection on the darn thing would corrode and go into the some times it works, some times it doesn't mode. Fuel pump went out (so he thought) dropped the tank, found out that his real problem was that all the wires to the fuel pump got green and fuzzy and kind of broke off, he fixed the wires it ran for another 5 years. Seems like the alternator went out at about 350,000 miles and at that time they scrapped it, as you can probably guess you probably have wire problems someplace, and as you probably know it'll cost you about $1.00 to fix it and $500 to find it, isn't life in these modern times grand? yes I know things are tight in there and you can't reach 1/2 of what you need to reach, start cleaning contacts and spraying them with dielectric grease until you get from the battery to the alternator. the other thing you might consider is going to a bone yard and if you can find a tracker get a new used alternator pig tail so you can plug into the alternator and play with it (checking wires, reducing the voltage on the sensing wire....) meanwhile pick up one of those jumper/booster packs for her to carry in it, in my experience once you do that the problem goes away.
 
You've mucked around and thrown WAY too much time and $$$ at this already.

Time to get serious.

NO need to cut anything.

Grab 3 lengths of spare wire and tuck the end of one under the nut at the large output stud, and poke two others securely into the terminals at the 2-wire connector (removing the alternator, if necessary to do this), and keep track of which is which.

Put 'er back together, you now have three remote test "terminals", start 'er up, check the voltages at all 3, and let's hear what you find!
 
Is the 80 amp fuse accessible? if it is, check the voltage from chassis ground to both sides of that fuse. That fuse should lead back to the starter Battery connection, or a stand alone lead from the positive terminal on the bat. If there is no alternator output at the fuse, it is a connection. Jim
 
Yes the fuse is one of the few things that can be checked pretty easy and while I have not checked it with it running I have battery voltage on both sides of it. I did try to pull it but only thing doing that did was mess up the case but the fuse it self is still intact. I even tried to jump across it while running and still charge from the alternator
 
Charge terminal yes that can be done and I have been thinking about doing it and got straight to the battery post and seeing is that changes things. The 2 small wires the back side of it the plug is sealed and to stuff in wires from the front and then plug it in well as tight as it is no way. Only way I can see to check that is to strip back a small area and splice into them and if I do that yes I would go wit ha color code to make sure I knew which was which
 
(quoted from post at 22:20:13 09/10/18) To be able to do that I would have to hook a wire to that post and then run it up and out some place because with it running you cannot get to the alternator. By the way to check for a good ground I checked it by shorting from the charge poet to the alternator body so I know the wire to the battery and ground are good

As for where I have been I have been here all along but if you read the opening line you might be able to figure out why I have not been posting and Hobo like always just showed he is one of the Y-T bullies
ep, finding real electrical problems is a lot more difficult than being a navy 'computer tech' changing dirty air filters on computer cabinets. Get a new battery & start from there.
 
Old,
Sorry to hear there are bullies on YT.

If replacing the battery doesn't solve your problem, Try running a ground wire to alternator. If that doesn't solve your problem try running a second wire from alternator + back to battery + and install an ammeter in the + wire.

This should eliminate any wiring problems.
 
I know nothing about Geo Trackers but have found out over time that the best answers to model specific problems usually come from forums that specialize in the subject at hand. That's not a knock on these guys because they are a smart bunch for sure but usually a person finds that if he is having an issue, many others have had the same one and they will say "go here and look at this,,," I did bother to find you an active Geo tracker Forum and link it here. If you cant figure it out they seem like a reasonable bunch of guys.
Geo Tracker Forum
 
I know you have probably checked this but those battery cables used to be prone to corrosion inside the terminal connection where you couldn't see it. I fought with one acting like you're describing, checked everything and finally cut the hard cover off to find a green mass of corrosion. Replaced the terminal end and no more problems with that. Just a thought, Keith
 
The 3 circuits you have at the alternator are all power with key on or engine running, ao you are good there. The two small wires get power from the same fuse (ign coil/meter). The large wire goes directly to the battery with the inline 80A fuse. So, the only things left are if the actual connections at the alternator are good, the alternator case ground, connections at the battery and battery.
 
If that fuse is bad it won't run. It's bolted in at the bottom so if you blow it you have to remove the fuse box to get to the leg bolts. Got that t shirt.
 
(quoted from post at 06:09:07 09/11/18) I know you have probably checked this but those battery cables used to be prone to corrosion inside the terminal connection where you couldn't see it. I fought with one acting like you're describing, checked everything and finally cut the hard cover off to find a green mass of corrosion. Replaced the terminal end and no more problems with that. Just a thought, Keith

Yes! Had that happen on a '76 Ford F100. It would start, and then it wouldn't. Replaced the alternator, and then replaced the voltage regulator. Turned out to be the positive battery cable. Absolutely NO outward signs of any corrosion but when I scraped away the insulation, there was almost nothing left of the copper wire.
 
I know the case ground is good I checked that yesterday by shorting the charge wire to the case and got the sparks I know I should have. As for the connections at the 2 wire plug I did all I could to clean them up and that is where I slip in the VOM lead to check that both have power. Car starts and runs so battery cable connections have to be good. I changed the battery yesterday and she got home with it but then stalled it and had a no start again. All appears to be as it should be but still it does not work like it should be
 
One of the first things I did was took the cable end off the - side and cleaned it up. It has those cheap clamp on battery cable ends and they where there when we got it. I guess maybe I should do the + side also and if that does not help maybe buy all new battery cables and put them on
 
I pulled the battery out of the Oliver 77 and put it in and changed nothing. Trouble shooting is part or being an E.T. in the navy but this one is one where the trouble shooting so far has not found the problem
 
I will add a thought here. Grounding.
Start with battery to body. Then battery to engine block. Engine block to body.

Consider - as vehicles age, connections deteriorate. Engine, body, and battery are three separate units. There connections that connect the three together. They may be mechanical connections like where things are bolted together, cables between two of them, or connections through combinations of the two. A bit of body corrosion in a strategic place can break a connection.
Is it clean and tight where the alternator bolts to the bracket? How about the bracket to the engine? Is there a braided cable between the engine block and the body?

Another thought is that you may have a connection that appears to check good until it is put under load. The voltage may be good while it is sitting in the driveway idling, but not be able to carry the necessary current to operate the vehicle's electrical system under driving conditions.

Another random thought that I had was the voltage regulator. Where is it? On some vehicles, it is an external unit. On others it is built into the alternator. On others yet, it is built into the engine's ECM. If yours is in the ECM, it could also be the problem.

Electrical problems can be difficult to pinpoint.
 
(quoted from post at 11:29:24 09/11/18) It has those cheap clamp on battery cable ends and they where there when we got it.

wow, I am really surprised you have not fixed it right and gotten rid of that walmart parking lot fix back when you first got it.
The battery cables are probably hard and crunchy when you bend them too.
 
Hello old,

You did what? Sure like to know where you got that test procedure. Looks like you are not going at it in a way it should be done. You may get lucky and find the problem. Good luck!

Guido.
 
I believe in if it isn't broken don't fix it or it will be and they have worked for 7 plus years now. I just cleaned all the connections at the battery and cable ends where they clamp into the battery clamp are nice and clean and bright. I even added a new body ground going right to the battery and that did not help. I'd do more but the wife has to go to work shortly so can do no more till tomorrow. But she will at least have a jump box with her this time
 
I can vouch for my friend Jim,,he found a bad connection on my FORD 2000,it was corroded,sometimes it worked,,sometimes it didn't,,Jim found it,,I never would have
 
I just installed a new battery to body ground wire and that did not help. I also cleaned the + connections on the battery cable. V.R. is internal to the alternator. I'd do more but wife is going to leave for work shortly so will have to work on it more tomorrow.

Tomorrow I plan to run a new wire from the alternator charge stud right to the battery. Plus add extra leads off the 2 small wires so I can check voltage to them while running and also be able to jump right to the battery to take out wiring problems some place in seen.

The odd thing is when I installed the first alternator it read 14 volts running but that did not last long
 
What I did was take a short jumper wire and put one end on the charge stud of the alternator and then touched it to the body of the alternator. That is an easy way to check for alternator ground and also the check that the wire going from the alternator to the battery is good. Ya I know not the best way to test things but it works doing it that way.

The odd thing is when I put on the first alternator and check for it charging I got 14 volts at the battery when running but after the wife took it for a drive it went back to 12.5 volts running or not running. So took that one back and got another one and had it checked before I left the store. Installed it and still not working
 
Old,
I think when they bench test a 3 wire alternator, don't the connect +12v to the two small connections on alternator. When I wired my 3 wire alternator one of those connections is powered by my idiot light and the other wire gets the full +12v from Ignition switch.

Perhaps someone can tell you if I'm correct. Then just hot wire your alternator by applying the +12v to the two smaller wires. If that doesn't work, all a wire from the negative of the battery to the frame of the alternator. If the alternator doesn't wake up, run a wire from alternator + 12 volt back to battery + and if you have an ammeter put that in the wire too.

Let me know if I got it right?
 
You didn't say what year your machine is in this post. In some of the later units the charge control was not internal to the alternator, but was controlled by the engine control module. Delco SI alternators actually make three phase AC, and you may have diode or rectifier problem. I have a PDF copy of the Delco SI alternator service manual I could email you if you'd like. I don't think my email is open on here so campbell dot ianc at yahoo dot com
 
Yes if I where to hook al 3 wires to the + side of the battery it should charged no matter what. If good that is. My plan for tomorrow is the run a new 10 gauge wire from the charge stud on the alternator and also tie in 2 pig tails to the other 2 wires so I can then apply 12 volts to each one and see if it will charge then. If it does then I know I have a bad wire some place and the way this thing is wired finding it will be hard to do. Years ago I had a 1991 Geo Tracker that we thought the computer had gone bad but latter after spending $400 found a wire has shorted out to the block which caused the ignition fuse to blow and that was a real pain to find and figure out
 
It is a 1997 Geo Tracker. Alternator is not a true Delco 10SI but one that works like the 10SI. As far as I can tell by the wiring diagram the Chilton's manual has in it. One thing that get me is the first new alternator I installed work for a little while then stopped working so figured I had a bad new one. So took it back nd got another one and had it bench tested before I left and it was found to be good. Installed it and still not charging.
 
Well so far my luck has not been all that good on this. But maybe tomorrow I'll figure out which wire is not doing it job. Might be even better if some one would hit it in a parking lot or some such thing so the other persons insurance would have to buy it. LOL
 
Just asking..

By the Battery is a small box with four fuses. Did you check the Alternator/battery fuse in that box? I am thinking it should be a 60 amp.
 
Old, post # 6 might be of help. 96 and 97 used the same alternator far as I can tell.

https://www.suzuki-forums.com/suzuki-sidekick-escudo-vitara-geo-x/52492-another-alternator-problem.html
 
That is the 80 amp fuse I have checked and double checked and t is good, but when I tried to pull it out I could not do so and the case broke. I then took the 2 wires from both sides of it and jumped across then to see if that did any thing and it did not help
 
I did have to splice but at all 3 as I have said on part 2 I get battery voltage. 12.5 give or take. Tomorrow I am gong to try to do a magnet test while running with something small so if the alternator is getting excited it will hold it in place. I have tried the magnet test with a wrench but where it sits I cannot tell it there is any pull or not. If I find no magnet action tomorrow I will try to take the 2 jumpers I spliced in and put ends on and then hook them to the connections if I can see/reach them that is. At this point I am thinking it could be a bad connector which I cannot find a replacement for. Had a gal at the parts store looking for one for around 30 minutes. Only good thing about that was is she is a young good looking gal LOL
 

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