Can somebody say if the schematic in attachment will work? Unused pin of PHR is connected to the negative so it becomes case negative, and also the host is case negative...
As long as the case pin is connected to the negative pin and your negative "line" continues to the negative contact of the battery, it will work. I am assuming a switch is "off diagram."
It was just fast drawing, but the phr is case nagative, and its negative pin is connected to flexdrive ld-, and its case is connected to host which is case negative also. Battery negative is connected to host case and battery positive to positive input of fexdrive. And flexdrive ld- is connected to positive pin of phr.