70 rallye dash wiring issue

[70phoenix]

Working on a 70 charger with a rallye dash. The car is just coming back together. I have the motor in it, dash in it, and its all wired up.  I started it for the first time a few days ago. Fired right up, everything did what it was supposed to.  I started it again last night and sparks fly from under the dash.  Immediately I turn it off and disconnect the battery.  I grab a light and crawl under the dash. Nothing looks out of the ordinary.  I hook the battery back up and fire it up again.  This time I'm watching waiting for it so I can see where the sparks came from.  Again sparks fly but this time I see that they are coming from the amp guage.  Immediately I shut it off and disconnect the battery.  Again I crawl under the dash,  all the wires look good, on the backside of the Amp guage there is a nut on each terminal that wires rest against. The nut the red wire is touching has a bit of a electrical burnt look.  I did notice before I turned it off that the amp guage was pegged, max reading.  I'm using a original dash harness/motor harness etc. I inspected the harnesses before installing them for damage (none) and any terminal that had corrosion I cleaned.  

Anybody had this problem before ?  How do I fix this ?

Maybe a unimportant fact, But with just the ignition turned on (car not running) there was no spark. The spark came after it was running/started.

[Pete in NH]

Hi,

Sounds like the ammeter post with the red wire is shorting to the dash frame or there is something inside the ammeter housing that is not right. Likely the vibration from the engine running is causing something to move around. Both ammeter posts are hot with 12 volts on them and are in the charge path between the alternator and battery. there is a fusible link on the battery side that is going to let loose and melt sooner or later if this sparking condition is not corrected. there should be some cardboard like insulator pieces on the ammeter posts to keep them insulated from the dash frame. Make sure they are in place and that both nuts on the ammeter posts are tightened well and there should be lockwashers on them. This is a good place to use both external  tooth lockwashers to bite into the terminal lugs and nuts as well as nylock nuts.

[70phoenix]

I was looking on here and several people are talking about a ammeter bypass. Is that the best cure for my problem ?

[Pete in NH]

I don't know about being the best cure for your problem. But, it is a way to address it. Take a look at the thread below on this page about bypassing the ammeter in a 73 Charger. I think you might be easily able to correct the problem, it could be just a loose connection or misalignment of the insulation on the ammeter.

[b5blue]

The insulator under the nuts is most likely at fault. I recommend installing a new OER brand gauge, it's rated to handle 60amps. Never start the car unless the battery is full charge and very good condition. Nyloc's may not hold due to the repeated heating cycle from recharging the battery after start. 

[RAC95054]

Something similar happened to me before, and it ended up being the insulator in the alternator has worn out, and was shorting the circuit, which eventually burned up the fusable link, but not before a few other wire connectors melted, and the ammeter was also pegged in my case.  Once you fire up the engine and it all starts to vibrate, the insulator was moving around (the ammeter needle moving back and forth) until it finally failed completely.

But also on the ammeter, you need to make sure the insulator strip between the housing and the terminals is intact and not fried, else that could also be the issue.

[The Mopar Kid]

I remember the first time my mopar burnt down. Life changing lesson.
Your best REMOVING THEM FROM THE AMMETER and connecting them to themselves or through an external gauge until you buy a new 100 dollar ammeter.

[70phoenix]

thanks for the help