Sorry about the late reply MT , I don't have the free acess to a computer all the time .
You're right about the baking soda , it wasn't in your old coolant post long ago , I still say plain water isn't good as most tap water is
' hard ' and creates deposits . I use distiled water with coolant .
I don't work on late model stuff BTW , only vintage and I don't even own a modern car / truck .
The relay does indeed protect the horn button contacts as the horn pulls much more amperage than the relay does , that is the _entire_ point
of relays , they switch the operating current instead of the horn button or switch thereby protecting it from wear/burnout .
Just testing horns is find but as I said : I get
" dead " horns for free and rarely cannot fix one
by carefully filing the points then correctly adjusting them .
_ALL_ of my posts here have directly addressed the questions asked .
Sorry we got off on the wrong foot so long ago , please feel free to bury the hatchet , just not in my back or truck , 'K ? .
I don't know sh*t , I think that is _OBVIOUS_ .
I dunno why they don't use relays in heater blower circuts , it sounds like a good idea to me
