[HO455]

Originally Posted by Minkota

The measurement was taken at the battery. That is why I was questioning it.

A couple of thoughts. First check your voltmeter on a different vehicle or other 12 DC source. Nothing more frustrating than searching for a problem that is in your meter. Don't ask how I know.
Check the battery voltage with the engine running, then move the positive lead to the alternator output post and compare the readings. They should be within .25 volts of each other.
If not mostly likely there is a bad connection in the wiring. To find the voltage drop place the black lead on the positive battery post and put the red lead back on the alternator post. Ideally you should read zero.
If the meter shows the missing volts from the first test the bad spot is on the positive side of the circuit.
If you get zero volts then put the black lead back on the negative post and move the red lead to a good ground on the alternator case. You should see the missing voltage.
Once you know what side of the circuit has the voltage loss you can divide that side of the circuit in two and test.
For example say the test on the negative side read .05 volts. You would then move the red lead from the alternator case to a good ground on the frame. If you're still seeing voltage then go to where the negative lead connects to the truck. If no voltage is read then check from the frame to the alternator case.
You may find it necessary to check the individual connectors on a cable to pin point the problem.
The theory behind this is a perfect wire with perfect connections will not drop voltage so the meter will read zero volts. But if there is a bad connection resistance is added to the wire and the voltage will drop. A volt test across the bad connection will show that voltage.
Good luck and keep us posted!