Which terminal at the regulator has the 14V? If the "Bat." terminal is showing that voltage the problem is between the regulator and the battery, possibly an internal open circuit at the ammeter. Temporarily, remove all the wires from the ammeter and bolt them together. If the voltage rises at the battery terminals, replace the ammeter.
There are several other possibilities. You really need to find someone who can do a detailed circuit trace, as it's almost impossible to cover all the possible problems long distance unless you have an extensive background doing electrical work.
The "new wire harness" concerns me- - - -there are a lot of ways to get a wrong connection.
Jerry
