electrical help

[sniper87]

I recently relocated the battery to the hatch and now the battery wont stay charged and when the car is running the battery light is always on. I have checked the alternator and even replaced it too. Still no change. Is there anything i need to do to make sure the battery is charging or setup to help the alternator work correctly. It is still a stock style alternator. If anyone has ideas or even a wiring guide or place to get one for a 1990 gt i would greatly appreciate the help. It sux not being able to drive my toy around. I can drive it now but with the fear of getting stranded. I have been through many different articles on google and have not found anything helpful yet

[TexasT]

Is it even charging the battery? With the engine running are you getting voltage at the battery? Do you have voltage at the back of the alternator?

What are you doing for grounds? Good one from block to frame. Good one from battery to frame.

[sniper87]

Nope not getting any voltage at the battery. I have not checked the back of the alt because it is brand new, but i will check it this weekend. Ive got all the factory grounds in place. One on driver side head to body, one from block to frame by oil filter, and i have a ground from the battery to the spare tire well.

[dee]

Wire size used?

Also just because the alternator is new doesn't mean it's good.

[sniper87]

Not sure on wire size but it is the wire that comes in the taylor rear mount kit. A buddy had it in his car and didnt want the rear mount setup so i traded him for it. Seemed like it worked fine in his car but i dont know if they had an extra wire running to the battery or not. I have read that on a 2g alt you have to run a separate wire back to the battery but its been awhile aince i read that

[turbostang]

As mentioned above, you need to have a good ground for starters. The block to the frame, and from the frame to the battery. It wouldn't hurt to run it all the way to the engine block... to confirm ground, you can check resistance between the battery and rear frame, and alternator to the frame.

The charge wire SHOULD be all the way to the battery (on the correct side of the switch.)

[sniper87]

I moved most of the wiring out of the engine bay and under the fender. I didnt cut or splice anything. Took the switches apart and put them back together correctly. When the battery is charged the car runs fine just wont charge. I took pictures and labeled everything when i took it apart. The positive cable comes off of the battery and runs directly to the starter solenoid. I have a ground wire from the back of the head to the body, ground from block to the frame, negative side of battery goes to a spot inside the spare tire area. I have read that with the factory alternators there needs to be a wire that comes from it to the battery. Anyone ever experience that? If i upgrade to a 3g alternator would that solve my issue?

[twisted93coupe]

I don't know if this helps but I ran 2 1 op grounds from motor to frame. Then I ran one 1 op ground from battery to frame in back. It's always best to have larger ground wire then power. Make sure your using at least 2 op power wire from battery to distribution block where all your power leads run to if you have one or starter. I have not had any issues. FYI mines not a street car.

[91GriggsGT]

Not sure where it is, maybe on the back of the instrument gauge cluster, but there is a resistor some where that tells the alternator to charge the battery.

I remember when I gutted my instruments, I pulled that resistor and placed it inline with the charge wire. Stock alternator with a painless wiring harness.

Also, are you running a battery cutoff switch?

[sniper87]

No i have not put a battery cutoff in yet. I know to be nhra legal i have to have one but i dont see the need for one if i cqn only drive the car about 15 minutes before i start having issues because the battery is dying. I have not pulled the instrument cluster yet to check that resistor. I might have blown it when i first tried to start the car and did not have enough grounds hooked up. I might also need to check all of the fusible links as well

[danielhv]

Check the signal wires going to the alternator as well. As for your battery ground, you need to make sure its grounded to the frame. Not the body. I ran mine across the back side of the hatch, drilled a hole, and went through and grounded it to the shock bolt on the driver side rear.

Sent from my SAMSUNG-SGH-I747 using Tapatalk 4 Beta

[sniper87]

Cool. When i get some time ill try that. I really think that the issue is it is not grounded correctly. It was fine until i changed the battery location. Hopefully ill have a little time to work on it soon

[00pooterSS]

Sounds like the alternator is bad. The battery light is connected to the alternator exciter wire post on the back of the alternator and a fuse on the other end of the bulb.

So you have a fuse that powers a wire that runs to the bulb, the power runs through the bulb and out to the back of the alternator, that is the small wire, the exciter wire is what it is called. It has to have 12+ volts when you turn the key on in order to turn the alternator on.

If that wire is shorted to ground or if the alternator is bad the battery light will illuminate. The alternator will ground that pin when it fails and provide the ground to the light bulb on the other side of the light and that causes the light to illuminate.

Try disconnecting the small wire from the back witht the engine on and see if the battery light goes off. If so you know the alternator is grounding that wire.

[sniper87]

What if i have already changed the alternator out? I thought the same as you and took my old alternator to have it tested. I went to a couple of different autozones and a couple of oreillys and they all told me it was working just fine. Autozone ended up failing it to exchange as a warranty. They tested it and got the same results. Once i installed it. Same thing. Car runs for a little while but i can watch the voltage on my meter slowly drop as it is running because the alternator is not charging. Is it possible that maybe that exciter wire got hot and grounded out? Is there a good place to find a wiring diagram so that i can follow where each wire is supposed to go? I dont have a problem chasing wires. I just need to have an idea of where they are going so that i can make sure i m following in the right direction

[00pooterSS]

Does it work okay and then after it runs for a while it starts to act up? Or is it a problem as soon as you start the car? I have seen many alternators start to crap out as they get hot but work fine up until that point. So they will test fine on a test bench but not be worth a crap on the car after running for a while especially in the summer.

Check the voltage right after starting it and see what it is (after it has sat for a while). If the voltage is dropping as it gets hotter then the alternator is crap. It's hard to find anything remotely close to quality off of a parts store shelf anymore.