Re: 1984 merc 115 swtch box
It's normally recommended that you do, since failure of one box can compromise the other.
If you can accept the risk that the switch box you didn't replace could go out, leave it as is and maybe you'll dodge the bullet. If it's gonna fail, likely it'll be right away rather than later.
Here's the "party line" from CDI/Rapair:
"NOTE: If the pack is bad, it is recommended that BOTH packs be replaced if the packs are not manufactured by CDI or Rapair. If the packs lose ground, internally or externally, the packs manufactured by other sources usually have severe damage to the bias circuit and need to be replaced as a set. The packs manufactured by CDI will withstand loss of ground connection, normally with no damage to the bias circuitry. In most cases you will just lose fire."
This is of course, them assuming that the switch box died by losing ground. If that's not the reason for failure (and I'm assuming there's many causes for failure besides loss of ground), then the box just died and that's that.
HTH........ed
