I will look in my book Tony, But isn't there a small tiny ballast resister on the back of your gages attached to the circuit bored ? Could be that or a ground was lost, and or like said before a fused link at the bulk head, on the fire wall, I would unplug the three plug in's outside under the hood and check to make sure they are connecting good.
If this is a stock harness I will look and see witch one is the ammeter is in, I am sure you have three main plug in's under the hood on the firewall.
