Not Charging Battery

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Steve Sallenbach

Active Member
My alternator is not charging the battery for some reason. I switched out alternators and still no charging. I have not had the alternator tested but I can't believe I would have two bad alternators. Does anyone have a diagram of the charging circuit and the electronic control unit which is what I think controls when the alternator kicking in. The two trigger wires that plug into the alternator are completely dead after testing them with a power probe with the motor running. I see someone posted a manual for a 2009 LT but I have a 2009 turbo so it's different. Other than the charging problem, the motor runs fine. I have not pulled off the positive battery terminal while the motor is running, maybe I should. The battery light does come on after a short test drive. After the short drive, the battery voltage was 12.4 and started at 13.4. Or any other ideas?
thanks
Steve
 
ctuinstra

ctuinstra

Goblin Guru
Not a good idea to pull the positive while the engine it running. If by chance the alternator is working and you don't have a battery, you can over-voltage your entire system. While that may not be true on this particular vehicle, that is general knowledge for all vehicles. The battery can act as a regulator and without it, voltage can go all over the place damaging electronics.

I think you found the problem, or are at least on the right track. The exciter wire to the alternator should have 12v on it.

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Steve Sallenbach

Active Member
Chad,
thanks for the information. I just googled how to trouble shoot charging problems and one thing that was mentioned was pull the positive from the battery which I really didn't want to do, good thing I didn't. You make a good point on potential damage. As we all know, you can believe everything you read on the internet. I hope I didn't do something stupid like cut a wire or damaged a wire which means tearing into the harness. Seems like I will never get this thing done.
 
ctuinstra

ctuinstra

Goblin Guru
Steve Sallenbach said:
Chad,
thanks for the information. I just googled how to trouble shoot charging problems and one thing that was mentioned was pull the positive from the battery which I really didn't want to do, good thing I didn't. You make a good point on potential damage. As we all know, you can believe everything you read on the internet. I hope I didn't do something stupid like cut a wire or damaged a wire which means tearing into the harness. Seems like I will never get this thing done.
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Keep plugging away. You'll get it up and going. If this project was too easy, it would be boring. Our car has been going for a couple of years now and I'm still working out some of the little kinks. If I had nothing to do with or to the car, it would be boring. As much as I would love for it to be perfect, there is just no challenge left or anything to do with it. Actually I'm very happy with the car and how well it has been and the problems have been relatively small.

Your issue seems to be easy to tackle. It should be a positive wire going to alternator and shouldn't be too bad to track down. Have you checked your fuses just to make sure there aren't any missing or blown?
 
Rttoys

Rttoys

Goblin Guru
Only old people that think them carburetors are superior motors, pull the battery cables when running as a point of diagnosis. :eek:

Don’t be like them :D


looks like you are on the right track with the diagram help.
 
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Steve Sallenbach

Active Member
thanks for the replies. Yes, that was the first thing I checked was fuses. I think I have checked them at least 3 times but will check probably 3 more times. The short time I drove the goblin it was a blast, it is quick and responsive which is what I like. I hear you on things never being completely done, I have body pieces to make/finish along with some other things I have thought about which is why the chassis is still not powder coated yet, but it will wait till winter, just want to get it on the road and have some fun before the snow flies.
 
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Steve Sallenbach

Active Member
According to Chad's diagram, it may be in the connection between the key switch and the exciter/trigger wire that goes to the alternator. Does anyone have a pin diagram with that info? I tried to do a continuity test on pin 10 and pin 30 on both black multi-plugs that go to the ecm with the two wire connector plugged into the alternator and ignition on but motor not running. I used a sewing needle to stick into the plug so I'm not sure if I was making good contact or not. I'm not sure what else to do except try the same thing with the ignition switch wires once I know which pins to test. As a side note, I'm terrible at wiring, it's all voodoo magic to me.
 
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Briann1177

Goblin Guru
The diagram that Chad posted is more of a logical diagram than a physical one. There is no direct connection between the alternator and the key switch. The battery light on logic originates in the ECM, and then travels over the low speed GMLAN network to your gauge cluster.

Like what others mentioned, this is a super easy circuit to troubleshoot.

Unplug your generator connector and measure continuity from the gray wire on the connector over to pin 30 on the bigger ECM connector. Do the same thing for the orange wire, but over to pin 10 on the same connector. Those two end points are just straight wires so they should read <5 ohms regardless of key position.

Also check the fusible link that sits between your starter and alternator.

20200803_190318.jpg
 
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Steve Sallenbach

Active Member
Thanks for your help Briann1177! Hopefully this electrical idiot (me) can figure it out. I sure don't remember seeing any fusible link, but I hope there is one because that has to be the problem.
Steve
 
Rttoys

Rttoys

Goblin Guru
That’s on the big main wire. You need to look at the smaller wires on the side connector.

edit
well if you have 14v when running at that terminal at the alt and 12v or less at the starter connection, then you have a fusible link problem.

odds are it’s a 12v trigger feed problem.
 
ctuinstra

ctuinstra

Goblin Guru
Steve Sallenbach said:
Found the problem, both wires were broke at the junction where they merge into the large wire loom. That was a surprise but an easy fix, not sure how they were broken since the engine harness was never messed with.
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Great job! See this electrical magic is pretty easy sometimes.
 
Ross

Ross

Goblin Guru
My LSJ just turned on the red battery light on the dash, and the alternator is making a squealing noise.
The used-auto-parts-yard have $27 alternators for the normal Cobalt, but don't have my SC LSJ engine's alternator.
Looking at the form factor, the two alternators look the same, physically, but the LSJ one has a different electrical plug.
I am tempted to buy the basic alternator, and the normal Cobalt electrical plug, and solder it into my engine harness... I really don't need the rare 135A alternator. Will this work? I don't have the connector/electrical view for the normal Cobalt alternator.
Oh yeah, I need to keep the 6 rib pulley off the old alternator, as the basic one is a 5 rib pulley.
Thoughts?
18023


18025
 
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Vwsaabvt

Vwsaabvt

Goblin Guru
Ross said:
My LSJ just turned on the red battery light on the dash, and the alternator is making a squealing noise.
The used-auto-parts-yard have $27 alternators for the normal Cobalt, but don't have my SC LSJ engine's alternator.
Looking at the form factor, the two alternators look the same, physically, but the LSJ one has a different electrical plug.
I am tempted to buy the basic alternator, and the normal Cobalt electrical plug, and solder it into my engine harness... I really don't need the rare 135A alternator. Will this work? I don't have the connector/electrical view for the normal Cobalt alternator.
Thoughts?
View attachment 18023

View attachment 18025
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It should work, lsj spins counter clockwise and is a clutched alternator. The 2.2 spins clockwise but isn't clutched so it should be able to charge Either way it spins. Lsj-t's use the setup off of non supercharged ecotecs since there is no longer a S/C. One thing that may differ could be the alternator bracket though since you will need to keep the lsj one since the tensioner set up bolts to it also.
 
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