1972 k20 gauge problems.

[low1954]

I have a 1972 chevy k20 that is still somewhat
New to me. I have been making updates to the
Trucks suspension as well as cab weather stripping, and have installed a
Tachometer. I had noticed when driving the truck home to Washington
From California that the amp gauge really didn't move, and even with
The truck turned off and battery disconnected it still read the same. I had also had intermittent problems with the temp gauge being sporadic, and now just pegged at all times, even with the battery disconnected. I have now
Ordered a three gauge cluster, for accurate readings, but still would
Like to figure out what's going on with the stock amp and temp gauge.
The green wire is connected to the sensor on the manifold, and I traced it into the wire harness over on the passenger side of the truck down by the starter. I would assume that it goes into the harness and into the cab to the gauge cluster? And was wondering if the wire is still green in color, of I need to trace a
Ground issue? Any and all help would be awesome. Thanks Jeremy