Should a diode be used with a relay from upfitter switch?

[2020Raptor]

Wow...this is getting involved.

 

[bryanb]

I do not understand how there is any "low" voltage side.
12V is just 12V everywhere, no ?

I don't think I said anything about "low voltage" but I did make a distinction between high and low current (amperage). The current through the diodes in your picture will be quite high. My advice is not to build what you drew.

 

[2020Raptor]

Thanks, understood.

You input is appreciated.