this is "notes to self" for now.

Electrical cleaner

 inc connector removal (but do not use but conne tors) The argument about using solder or not in automotive joins rages on. In this one there is a nuance "use a tny bit of solder only". 

The argument against solder is that over time the join becomes fragile and breaks. As far as i can see the current popular method is .. always being argued! 

 Except that the MFRU interlinks relays to work together, hence "multifunction". Not figured out what yet.

Circuit breaker