There is debate about the best way to repair electrical wiring on farm equipment. In a perfect world, the preferred method is to strip back the insulation on the wires to be spliced, mechanically join them in a twined splice, then use solder to lock the splice before weatherproofing the joint with heat-shrink tubing.
In the real world we usually end up with a ragged, twisted splice between the wires, with several stray wires bristling from the mess that end up poking through the heat-shrink tubing once it is shrunk. But before we slide the heat-shrink tubing into place we try to make everything "nice" by globbing on a pound or two of solder, so that the spliced, soldered and heat-shrunk wire ends up looking like a snake that swallowed a big rat.
If you have the skill and patience to make tidy, tight mechanical splices and then "silver" them with solder before heat-shrinking the area, that's a great way to repair wires. But "stuffed snake" wire repairs have a tendency to cause problems because the flexible copper wires tend to fatigue and break at the edge of the soldered mass, if the wiring harness is subjected to a lot of vibration or mechanical motion.
That problem with wires flexing and breaking at the edges of poorly soldered splices is a good reason to use heat-shrink electrical butt connectors to make repairs to wires. Those connectors are fast, mechanically strong, weather-resistant and relatively tolerant of vibration and mechanical abuse. They also eliminate the need to have a soldering iron or gun for field repairs.
Don't be tempted to use the old-style butt connectors without heat-shrink insulation. Those old-school crimp-on butt connectors are not moisture resistant and often cause big problems with corrosion, high electrical resistance and eventual failure down the road.
New-style heat-shrink butt connectors are worth their extra cost because they are not only moisture-resistant, but their tight fit on the wires when "shrunk" provides additional mechanical strength to the final connection, yet that plastic area is has enough "give" to reduce problems with breakage due to vibration or motion.