Years ago as a gofer, I was taxiing a brand new PA31-350 that had just completed it's Aussie CofA (circa '78) when a multitude of warning lights came on, including fuel warnings.
Investigation revealed a plastic electrical connector of the male/female type with a multitude of cables running in to each terminal block.
The problem was that the male part was several sizes too small for the female part, and was held in place by a plastic zip-tie!
