[Jay]

The black/white wire is the +B wire to the coils.

 

[Jay]

Sorry. +B = Plus Battery. You correctly identified the BLK/WHT wire.

As you probably already know, if the coils are pulling +B down to 3V then one or more coil packs is shorted, or the BLK/WHT wire has too much resistance, or both. I think if one of the coil packs had shorted it would blow fuse #1 (15A) in the under-dash fuse box, so I'd make a resistance check of the wire from the coil packs to the fuse.

 

[Jay]

The fuse box sounds like a likely suspect. You can run another wire to the coil packs to supply +B, but then you have a problem (and a possible fire hazard) if something shorts on the wire or the coil packs short. You really should fuse the supply wire. Also, you make things a huge pain for the next guy to troubleshoot. Much better to clean up the existing connection if that's the problem. Maybe you don't need to replace the whole box.