I can attest to using "Shower mode" on the rinse water as I learned power washing the ATV's off after a weekend of mudding.. Blew the stickers right off on the final rinse LOL I can imagine how that would drive the water into the connections and start a problem for later on ... Good tipWrap any electrical connections (like the battery terminals) in a plastic bag and tape in place, and liberally spray the engine bay with Simple Green. Let sit for about 5 min, hit any excessively greasy/dirty areas with a toothbrush, then with your hose sprayer on the shower setting rinse. Do not use a lot of water pressure.
If you want it to really sparkle, hit the engine bay with armor all after it dries, but that will draw more dust, so I sorta recommend against it, but it does look nice while it's still clean.