Alliant AP0015 Repair Harness for Injector/Glow Plug connector repair kit for the exterior plug. The spliced connections should be soldered & sealed. This will prevent moisture and dirt from causing corrosion and insure good conductivity especially in low current circuits.
It is recommended to use waterproof shrink tubing on the spliced connections. All you will need is a set of wire strippers, soldering tool, heat gun, electrical solder and some weather tight shrink wrap.