the Super ELECTRICAL Mystery - New Batt. Alt. and Starter NEED SOME HELP [Archive] - Forum


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11-08-2009, 09:21 AM
Hey whats up. I have a 2000 GAGT 3.4L . I swapped the motor (put in a 99), everything runs fine except the battery light always comes on and stays on. So far I have a brand new starter because the old one did not work. I have a brand new battery. I own 2 GA's so I have also used the battery from it too. Each time I have drivin for a bit, I removed and charged up the battery to run the car with a fully charged barttery after the next test run. I have had 3 alternators on this car. One was off my other GA. One was from the old 2000 motor and one is a 1999 re-man I got from Auto Zone. Auto Zone had tested and passed all 3 alternators on the in-store machine. I have also had the car bench tested at 2 different stores by 3 different people. Battery and Starter all pass. The reading at the battery is that the Alternator has a low amp output and it only reads at 12.15 volts instead of 13 or 14 (whatever its suppsed to be). So the other thing I have already done is clean and reattach all grounds. I CANNOT FIND ANY GROUND RIBBON/STRAP, if that matters or not? Where can I attach one if I need it? I have also disconnected the neg. battery post and with a check light pulled every fuse to try and find if there is a drain somewhere but the "check light" never goes out on any fuse, even with the alternator unplugged. I am heading out of town for the week (wanted to take this car but no luck) anyone have any ideas I'm all about it. Thanks for reading :) I have no extra electrical items in my car. All stock lights and stereo. I have many performance mods including RSM Supercharger. Old motor ran with no electrical problems in the exact same scenario. THANKS!

11-08-2009, 01:12 PM
Id check the power wire from the alt, it has a fusible link. Maybe that link is blown.

11-08-2009, 04:23 PM
Id check the power wire from the alt, it has a fusible link. Maybe that link is blown.

yup i'm with him. Same thing happened to me. All i did was i bought some 0/1 gauge wire and ran it straight from the alt to the positive battery terminal. After some time like a week or two the light went off and never came back. Also make sure you remove the old output from the alt to the battery. Just disconnect it and cover it up so it won't touch anything

11-08-2009, 07:53 PM
Check your grounds and check the power wire from the alternator.

Also, just because an autoparts store tests your alternator and says it's good, doesn't make it so. I had my old alt tested at advance auto parts and they said it was good... but the voltage kept dropping in my car while the engine was running. The voltage regulator on the alt was bad. Got a new one and right away had 13+ volts.

It should take less than 12 volts for your battery light to come on. It may drop below that though when you start driving and are running accessories. If you are only seeing around 12 volts at the battery with the engine running, I would say you aren't getting enough power from the alternator. It's probably running mostly off the battery until it gets too low 'cause the alt isn't charging fast enough and then the battery light comes on.

btw, I also did the wire upgrade from my alternator. Ran it straight from the positive post to the wire coming from my battery that also connects to the starter and the fuse box. Problem was I draw power off that for other accessories too, and that provides power for my MSD ignition. Ran it like that for a couple months then suddenly my MSD quit on me. The tech at MSD claimed that the direct power from the alternator was creating electrical "noise" and would keep the unit from working properly. Don't know why it worked that way for several months then but... I had to disconnect that wire for it to work again. I also had a fried coil I had to replace.

Take that as you will, but if you run extra accessories that need positive power under the hood, you may not to run your alt wire like that. I'm taking my 4ag wire and going to replace the stock wire with it, running it to the fuse box with a fusible link like stock.