Be careful with the panel out, and be careful not to get down a rose paved crooked path.
Part of what I mean is, you may or may have disturbed a poor connection in moving things around, which may temporarily hide the problem,---or may it worse.
Also you are unhooking the ammeter itself which may be part of the problem (by removing the cluster)
"The usual" circuit for voltage drop is illustrated somewhat in the simplified diagram from MAD electrical concerning the ammeter.
Basically, ANY POINT in the path may cause drop. From the starter relay---fuse link-- through the FIREWALL CONNECTOR (large RED to ammeter)--through the ammeter--to the WELDED SPLICE, the LARGE BLACK to the ignition switch CONNECTOR, through the SWITCH, back out the switch CONNECTOR (now on the dark blue "run" wire, back out the FIREWALL CONNECTOR--and to the ignition system, the alternator field/ VR etc.
So in your case at the cluster, you can eliminate the last section back out into the engine bay, but everything else applies
ALSO REALIZE that EVERYTHING must be connected as normally as possible to test, because CURRENT through the circuit is WHAT DRIVES THE DROP
[URL]http://www.madelectrical.com/electricaltech/amp-gauges.shtml[/URL]
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