RM 8501 wiring issue

On my old unit all I had was + (black) and - (white)  I do not like mixing wires of different color so what am I missing?  According to the plastic cover box I would connect the existing white ground  to the black line (-),  above and existing black line to the purple line (+) above.  That doesn't seem right to me.  If any of you can look at the back of your RM 8501 and tell me what you have, it would be appreciated.  No call back from FR today.  Hopefully Monday next week.

Thank you Offgrid !!  I didn't see that wiring block as it is located real low ( I didn't get down on my belly to see this) on my original it was located and screwed on the top of the refrigerator where one can easily see it.  Anyway, my original was not hooked up to the heating element - it appears from the schematic on pages 43 and 44 that this is for a heater in the door?  What is the advantage of that?  Will this minimize the amount of ice buildup on the aluminum fins or what?  Also will this eat up a lot of battery if this is running all the time?  Any ideas of amperage use for this heating element?

Yeah, I hear you.  The mold nowadays is smarter than it was 20 years ago!  Anyway, my brother just sent me a text about this and told me that on his Dometic (5 Cubic foot) 2017 model year that the condensation heater for the door draws 0.5 amps or 6 watts.  That works out to be 12 amp hrs./day.