CobraStangGT16

My battery light went off after I got a spark from the alternator wire. Iforgot to disconnect the battery andI hit metal with it by accident and it let off a spark. Now my car isn't charging and I have a battery light.

I checked the main ALT fuse under the hood...it's fine. There are 2 fusible links, butI don't know where they are, and how can I check if they are bad?

If the voltage from the alternator output wire is showing 12v when the car is running, can that still mean there is a blown fuse? Or does that solely mean that the alternator is blown?

Thanks guys...my car is having major problems right now. I have no idea why.

CobraStangGT16

bump...anyone know?

Derf00

Have the alt bench tested. That will help rule out the alternator. After that...I don't know where the fusible links are on your year. I believe there is one coming off the battery wire from the back of the alt. Check it for continuity.

CobraStangGT16

My alternator can't be bench tested at local auto parts stores. I've already tried it before, neither can most 99-04 GT's I know of.

I ruled out the underhood fuse in the power distribution box...the one right behind the battery...that fuse is good...but how do you check for a bad fusible link?

cliffyk

The fusible links look like two pieces of gray 12 ga. wire, coming off a large terminal post at the inboard side of the main fuse block under the hood. The positive wire from the battery feeds this terminal, and the fusible links feed a black/orange wire that descends beneath the battery.[/align][/align]You may have zapped the voltage regulator--unfortunately, like most modern designs it's integral with the alternator. However a local auto electric shop ought to be able to test it.[/align][/align]

CobraStangGT16

Cliff,

How does one "zap" a voltage regulator?

I thought they just had brushes in them?

cliffyk

Voltage regulators used to be acombination of voltage and current relays (two current driven, one voltage driven) that controlled the battery charge voltage. Those days are long gone and the modern voltage regulator is an electronic device, which like most other electronic devices doesn't like voltage spikes--which unfortunately are what is created by sparks.[/align][/align]The brushes you refer to were in the old daysa mechanism for transferring thevoltage generated by the armature to the outside world, however an alternator is sort of like a "reverse" generator and the brushes pass a control voltage to the armature (rotor, really). In the old days of generators the brushes rode on a commutator (a series of copper bars laid out like railroad ties and connected to the armature windings) and got chewed up long before the bearings failed--with alternators the brushes ride on continuous "slip rings" and usually outlast the bearings and electronics.[/align][/align]The raw output of an alternator is actually 3-phase AC (at 130V or more if pushed all the way), at hundreds of cycles per second. Diodes in the alternator convert this to DC, and the electronic voltage regulator sees to it that the rotor voltage and current are controlled so as to provide the proper charging voltage (13.8V) to the battery and run whatever accessories you have turned on.[/align][/align]Short story, the arcing you accidentally created may have zapped the electronic voltage regulator.A good auto-electric shop should be able to test the VR (and diodes), and replace just what's fried--however often it's less expensive to just buy a rebuilt unit at your FLAPS...[/align]

CobraStangGT16

OK Thanks for clarifying...you've got to be the most genius person on this site.

I JUST had the voltage regulator swapped out like 3 weeks ago because it had no brushes left in it...so the guy charged me $115 for swapping it out, and putting it back on my car. It worked like a charm.

The advantage I have here is that the guy who did wrote me a LIFETIME WARRANTY so that if it ever goes out for any reason, just bring it back and they'll take care of it...so I may be able to get it fixed free of charge...

Thanks again, buddy...I really appreciate your help.