I have one wire which is broke and bad from under steering wheel to computer- I just purchased a new computer. Do I need to replace the wire; solder and wrap it or buy a new harness?
I don't want to ruin the newer computer or see it die again in a year.
Which wire? Which computer? What is the symptom? Broken wires are typically spliced, soldered, and sealed with heat-shrink tubing after the reason for the break is determined and corrected so it doesn't happen to another wire in that harness. Never use electrical tape. It will unravel in a gooey mess on a hot day. Complete harnesses are only replaced when the car is under warranty and the manufacturer is paying the bill or when one was crushed in a crash. They are very expensive and usually very time-consuming to replace.