I would recommend you take a look at Pantera Electronics, Radiator Fan Controller. Jon Haas is an automotive engineer and fellow Pantera owner.
The Radiator Fan Controller isolates the fans from the Pantera electrical system.
It decreases and increases the fan speed as needed. This is truly a work of art.
http://www.pantera-electronics.com/rfc.htm
Also take a look at the ATO Fuse Panel. This is a “plug & play” replacement. It eliminated electrical issues I struggled with for years.
http://www.pantera-electronics.com/fuse%20panel.htm
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