Gages

[Mancar1]

I hope someone can help me solve this.
I got the Shark gauges by Dolphin installed in the 68. When I turn the ign on the gauges power up and work for a minute. Then they drop down and the needle starts bouncing. I am scratching my head on this.

[Calfdemon]

Tough to trouble shoot without knowing how you have them hooked up. Each gauge should have 4 wires, right? Power, Ground, Light, and signal... How did you route your power? Do you have dedicated power to the gauges running through a relay that is turned on with ignition power? Or did you wire them into an existing circuit? And if so, what circuit?

And is it all of your gauges that begin to mis-read? If so, that eliminates the signals. If it is just one or 2 gauges, then that could be the signals or sending unit. If it is all of the gauges, and they start acting up at the same time, then that is either a power or grounding issue. Explain (or pictures) a little better on how you have them wired and if they are all screwing up at the same time, or what exactly is happening and I can probably help you a little better...

[Mancar1]

Had them all grounded in series. Must have had a loose connection. Because I now have them grounded separate and they work. There is a very slight bounce movement in the Tach, Volt, Oil, and Temp gauge, but hardly noticeable. The Volt meter is reading 12 so I am looking into why no charge from the new Alt.
A mess in the old wiring. I am considering buying a new harness and re-wiring the 68.
I am beginning to think I should have went Dakota Digital.
The two wires that went to the old Amp gauge, should they be connected together? I have them connected to each other at this time.
Thanks for any input......John

[Calfdemon]

I did away with my Amp gauge and am just running a Volt gauge which I wired with new wires. I just cut the old Amp gauge wires and taped them off in the cluster harness. If you re-grounded them and they are now working, then it looks like you solved your problem!

[Mancar1]

I now have a volt gauge. I did away with the amp gauge.
The old amp gauge wires from the harness. Did you hook them together and tape them off? Or did you tape them both off separately?

[Calfdemon]

I am almost certain that I just cut them separately and taped them off without them attached to each other.

[Mancar1]

That may b my problem. I hooked them together and taped them. I will check that out.
I wonder if the amp gauge on the bumps have a internal or external shunt.