Your problems sounds like a classic mistake of having the two wires in the alternator plug reversed. This might be because of the new harness or it could be because of the regulator wiring being crossed.
If the wires are reversed the engine may not shut off because of alternator feedback to the ignition switch and or not having a resistance in the charging wire. You are calling it a white wire which is was in the original harness. There has been some confusion as to what wires to jump in the original harness external regulator plug, which you may not have with the new harness.
If you do then you need to find the brown wire that comes out of the firewall connector by the master cylinder, which runs to the external regulator on the "F" terminal. It will be on the end of the plug. This wire will jump to the white wire and continue to the alternator and will connect to the no. 1 terminal on the alternator. The other two wires that jump on the plug are the red wire at terminal 2 on the EVR and the blue wire at terminal "4" on the EVR.
Here is the correct way to jump the EVR plug wires.
The result of having the wires reversed, is that the alternator will excite and charge, but it will not regulate the amount of voltage and current output because it cannot read the system voltage so it defaults to full output. This will cause it to overheat and overcharge the battery and possibly blow some lights. The diagram shows how the wires could be reversed. The correct way is brown to white and red to blue. Then at the alternator it will be white to no.1 and blue to no. 2.
I usually eliminate the jumpered wiring and run the brown wire directly to the alternator at no.1 and then run the red wire to no.2 as per the diagram below.
Some guys just loop a small wire from the large wire on the alternator over to the no. 2 terminal. This is the sensing wire for the system circuit and it activates the voltage regulator inside the alternator. This connection works, but it is not as efficient as the previous method, because it does not sense the voltage drop downstream from the alternator, so it does not compensate for that.
The blue wire will continue to the alternator and connect to terminal "2" on the alternator.
This is the conversion for the internal regulated SI series alternator, if you have the original alternator or the newer CS alternator then there are differences to the conversion.
We have to know what alternator you have for sure and what harness you have installed. Is it original or modified?
It will be helpful to know what dash cluster you have Gauges or Idiot lights.
Either one of these dashes should have a resistance in the wiring to the external voltage regulator brown wire,so no diode should be needed. The diode will prevent feedback voltage to the ignition switch and it does have some resistance so it works too.
Here is another diagram showing how to wire the alternator.
Check out what I have posted and get back with the results. VV