Electrical troulble shooter needed

[Scotty C]

I have a 428 FE in my Cobra . The alternator was tested bad . After replacing with 100 amp alternator the gauge on the dash still wont show a charge...only showing the draw from the fan ..blinkers.....lights etc.......bad regulator ??? or ground??? Thanks for any help......

[Excaliber]

Volt or Amp gauge?

[Scotty C]

Amp

[HighPlainsDrifter]

Hi,
The old style alt's are controlled by the separate voltage reg., so I would suspect that, or the ground [it has to be grounded,not screwed onto fiberglass]
If the alt was bad, why didn't you just get a 1 wire alt, simple with internal regulator.
Good luck,
Perry.

[Scotty C]

I just replaced the alternator with the same type that i removed...if i need to replace the regulator where is the best place to look....???( provided the ground is good..)

[HighPlainsDrifter]

Scott,
the voltage reg is a 2" x 3" black module, usually put on a fender or firewall. Follow the wires out of the alt and see where they go.
A 1 wire alt just has one large #6 wire going drectly to the battery, or through the amp meter in your case. I personally don't recommend running an ampmeter as all the current goes through it and can be dangerous if it shorts out. A volt meter is much safer and will tell you the output of your alt.
Perry.

[Excaliber]

Sounds like the amp never worked, before or after the new alternator? As in, it works exactly the same now as it did before?

If so, I think I know whats going on, but it's a lengthy explanation, so you go first!

[Scotty C]

Thanks guys...my dad is an old school mechanic....he assures me we can trace it .......if the regulator is bad where can i find one....???...thanks...

[Ron61]

Scott,

If you do have a bad rgulator you should be able to get one at any good parts store. An easy way to check if the alternator is putting out is just take a volt meter and put it across the battery terminals and rev the engine up. It should read around 13/15 volts. I use a voltmeter in the dash and mine reads 14 volts.

Ron

[bobt427]

To test the alternator on the car,and your amp gauge just hook a jumper wire from the battrey to the red or orange field terminal on the back of the alternator.That will make the alternator go to full output.

[SCOBRAC]

How is your car grounded? Every single area drawing current in a fiberglass car needs a ground wire. You don't mention if this is a new build or an existing car that only recently developed problems.

[Scotty C]

I pulled the rgulator and it was fried ......Im just not familiar with what the amp gauge is supposed to do . I think i have fixed the problem . When the car is running the Amp gauge doesnt show a charge. The needle stays right in the middle. When you start turning on accesories...fan , lights , etc...the needle goes to discharge and then slowly comes back to the middle. This must be what was intended.......Thanks for everyones help...!!!!!!........

[Ron61]

Scotty,

The amp gauge will normally run right at the center unless the battery is low and then is will show on the + or charge side until it gets the battery back to normal. The dropping when you fist turn lights and accessories on is normal as you are adding draw to the battery and the alternator has to compensate for it. So yours is working correctly now. Good luck.

Ron