My truck has been intermittently throwing the 3 amigos. When I scan it. It says back left road sensor fault. That hub is new.

My guess is the wiring to the computer went bad. So how do I fix this?

 

I would start by swapping sensors left and right, see if the fault moves.

 

Did that. The fault still carried over.

 

Just what do you mean when you say "carried over"? Do you mean the fault remained for the left rear, or do you mean it was "carried over" with the swapped sensor to right rear?

Wheel speed sensor faults are very often caused by problems with the connector where the sensor cable plugs into the wiring harness. If the fault is still right rear, I'd cut out the connector and splice the wires together. You can do a solder splice, or some here report good results using heat-shrink butt connectors (like those made by 3M). For either of those approaches, cover the splices with heat shrink tubing. There are other types of auto/marine connectors that would also work.

 

If the fault reoccurred on the same side after swapping sensors = look at wiring. If it followed the sensor = faulty sensor.