Resolved Alternator not charging battery.

[jakk220]

Long story as short as possible, my battery was dead everytime I shut the car off and it needed jumped. After I jumped it, it ran fine off the alternator. Ok... Dead battery. Replaced the battery, drove it a while, and got on into boost for the first time since my new transmission and the car was braking up at full boost.

Again, found out alternator was still not charging. At no time have I had a battery light yet. It puts out about 12v, enough to keep the car running apparently. So I replaced the alternator and had the new one tested before I put it on. Tested fine. I got the battery fully charged and put the new alternator on and still, 12v.

So I checked the wiring for the "charging relay diode fuse thing" and the blue wire was broke. Fixed that and made sure the bulb in the cluster was good, and still nothing changed. If I touched the blue wire to I believe the black and yellow wire it worked when the key was on Acc, but still only 12v.

Alternator fuse is good, I checked it. No other wires appear broken. I did disconnect the alternator harness from the alternator and it went up to about 14.3v at idle.

Im lost. Does anyone know what I should check next?

I was also wondering if someone could please post a picture of the harness for the alternator relay and where the wires go to it. I used spade connectors in place of the old broken harness but want to make sure they are all there and in the correct place. To my knowledge the car shoyld still charge with this desconected anyway though.

 

[91talonts1]

You don't insert the screwdriver directly in the pin. Sometimes the locking tab is below the pin, sometimes above. I can't remember which way it is on the alternator plug.
If you can see well enough, you should be able to shine some light on there and see it. It doesn't take alot of force to disengage it, but they are tricky and it takes some patience.

 

[jakk220]

You don't insert the screwdriver directly in the pin. Sometimes the locking tab is below the pin, sometimes above. I can't remember which way it is on the alternator plug.
If you can see well enough, you should be able to shine some light on there and see it. It doesn't take alot of force to disengage it, but they are tricky and it takes some patience.

Ok. I assume its probably in the hole below the pin then. Ill give it another try tomorrow. If I can't get it then Ill just send the ECU out. Which I will probably end up doing anyway to rule it out.

 

[jakk220]

ECU tested fine at ECMtuning. Now I'm officially out of ideas.

 

[91talonts1]

Did you check to see if that wire itself is grounding somewhere?

 

[boostdawd]

With all these electrical issues why not just do a saturn alternator swap. U would only need one wire to activate it and another for sensing voltage. Beats chasing this electrical gremlin.

 

[jakk220]

With all these electrical issues why not just do a saturn alternator swap. U would only need one wire to activate it and another for sensing voltage. Beats chasing this electrical gremlin.

That's definitely an option. But the only thing I think youre eliminating at that point is the FR and G which are working. Unless the wire itself is grounding out like @91talonts1 said. Ill test that once my ECU gets back Monday.

Is a bad engine ground possible? Like to the chassis? Because if the alternator uses the engine block to ground, maybe its not getting a good ground source.

 

[91talonts1]

That may be possible, not really sure. But the engine should be grounding direct to the battery via the starter cables and it seems the starter would stop working before the alternator.

 

[jakk220]

That may be possible, not really sure. But the engine should be grounding direct to the battery via the starter cables and it seems the starter would stop working before the alternator.

Yeah I checked all the wiring and everything is good. Like you said I'm not having any other symptoms to go with it. I just borrowed a power probe from one of my friends and am going to poke around with it when the ECU gets back Monday.

The only things I have changed recently are
1. I installed a new FMIC kit. Car ran fine after the install.
2. Installed new headlights and fixed some ghetto wiring that was done to them by highschool me.
3. The transmission blew right after the headlights were replaced and then I had it rebuild by shep and once it was put back together the issue was there. I also replaced my battery terminals with some nicer ones at this time.

So it could be related to one of those somehow. The red wire for the alternator plug goes the the "Headlamp" fuse. Which I assume is the headlights. Does anyone know exactly how the red wire is tied into them or what it does so I can investigate that?

 

[Vegas Smith]

I think the headlamp leads to the cabin where it branches to a million things. I think.

 

[91talonts1]

That one wire is tied into the headlight circuit as it's source of sensing voltage.
If it doesn't get voltage to that wire, the alternator puts out as much voltage as it can from what I've seen. Maybe it's possible it doesn't output anything if it doesn http://www.dsmtuners.com/threads/high-voltage-from-alternator-problem.511874/#post-153646114

 

[jakk220]

That one wire is tied into the headlight circuit as it's source of sensing voltage.
If it doesn't get voltage to that wire, the alternator puts out as much voltage as it can from what I've seen. Maybe it's possible it doesn't output anything if it doesn http://www.dsmtuners.com/threads/high-voltage-from-alternator-problem.511874/#post-153646114

Well I guess it wont hurt to check it anyways. But it seems as though you're right. It would have the opposite effect.

 

[jakk220]

Pic attached. The problem is finally solved! When installing my new vrsf intercooler and drilling through the support wit a small drill bit I nicked the harness and cut the wire from the ECU to the alternator. We finally figured it out with the power probe once we applied power to the alt harness and it started charging.

By buddy actually found the cut in it by only seeing one tiny strand of copper poking through the harness. Thanks everyone for the help! Back to the road now!

 

[boostdawd]

Glad u got it figured out. Such a big relief after u found the issue. Careful with the drill bro LoL.

 

[jakk220]

Glad u got it figured out. Such a big relief after u found the issue. Careful with the drill bro LoL.

Oh man the relief is insane. I've been working at this issue a minute now

 

[Hot Wheels]

Have you tried making sure the alternator has a good connection to ground? I've had to reground all kinda of stuff here in the south. Also, the generator relay appears to me to be nothing more than a half-wave rectifier diode, which would show on a schematic as a diode and resistor in series.