amp meter going crazy

[2man]

Had a weird thing happen to yesterday. While driving to work, i noticed my amp meter gauge going between + and -. A/C fan was going fast then slow. Is this an alternator prob or maybe just a lost wire or perhaps something grounding out? By the way those Accel Super coils sure pack a WALLOP!!!! :eek: :eek: :eek:
HOOK 'EM HORNS :D

[Tiger Shark]

Make sure to check out the wiring before you go and drop some $$$ on a alternator.... I made a mistake a couple of years ago with my old rig not checking out the wiring before bolting on a new alternator. It was a 1$ fix instead of the piles of cash i threw away on the alternator i didn't need.

[Bob Barry]

I have to second the opinion that it might be more than the alternator or regulator (though it could be either or both of those).

The '74-'85 ammeters were prone to turning themselves into toasters, taking out the main charging wire from the alternator through the big splice under the dash to the input on the gauge itself. You can tell this from blistered insulation on the wiring and a guage needle warped from the plastic body of the gauge beginning to melt. An actual dash fire is not far behind.

The ammeter can be bypassed by placing the yellow wire off the back of it on the same terminal as the red wire, taking it out of the loop and making its inevitable death a non-issue. But definitely check the condition of the wiring harness where that big fat red cable passes, especially at the firewall bulkhead connector, and check the condition of the yellow wire that comes back off the ammeter and to the battery.

Don't rule out the A/C blower or its associated wiring as well.

[joe]

Are the other gauges flickering too? Could just be a bad ground between the body/frame. For a quick easy check get a piece of large wire 10 ga or so or an old battery cable whatever you have laying around and clean off an area where something bolts to the firewall. Get the paint off down to clean metal and run the other end to the neg batt terminal. If that steady's out the gauges replace the temporary wire with a good ground strap or batt cable.

[WudreauxTWW]

Don't overlook the obvious... perhaps a loose fan belt??? I usually don't notice those types of things until I have spent some $$$ needlessly. :D

2Man... After seeing the way Tech played yesterday, I'd be a horns fan too.

[JohnnyJ]

Check for what Bob Barry said immediately, if not sooner!! I had the same thing happen to me on a road trip last summer and it toasted my brand new alternator and burned up some wiring behind the dash.

It is a real mess if it goes too far.