Originally Posted by 7T1vette

The ammeter leads are both connected to the same power wire in the harness. But, they are connected at a fixed distance apart (around 12" or so). That length of wire between them acts as a 'current shunt' and produces a voltage drop which is proportional to the current flowing in that wire. The small voltage drop on that length of wire is sent to the ammeter which is scaled to read "AMPS".

Although that sounds complicated, the wiring is very simple: two ammeter leads run to one [main] power wire and attached at a fixed distance apart.

You cannot run those ammeter leads to ANY location on that wire or at a terminal connector and get the ammeter to read correctly. They must tie into that power lead at specific locations for the ammeter to be calibrated properly.

Originally Posted by gavino

I understand the whole principle of the ammeter's workings. Your explanation is right on. My problem is that all my connections seem correct, I have equal voltage on both the black and black/white wires to the meter at rest. When I check the meter with a 1.5 v battery the meter pegs plus or minus, so it is working. I have a new engine wiring harness and both ammeter leads wind up on the horn relay. I am a 68 so I have a separate voltage regulator. Battery charges fine but meter doesn't move. The horn relay has two connect posts. Does it matter where the wires are attached to the bus on the horn relay? Something else maybe?