How to Rewire a Headlightby Matt Scheer
If the wiring harness that brings power to your headlight bulb is faulty, you can replace it yourself. The wiring harness connects to the base of the headlight bulb as well as the power distribution center in the engine compartment. No extraneous parts need to be removed to rewire the headlight, although the exact process varies by make and model of vehicle. You can purchase replacement wiring harnesses through a local auto store or through an online vendor. Expect the entire job to take about 30 minutes.
Turn off your vehicle. Prop open the hood.
Loosen the negative battery terminal nut with your crescent wrench. Lift the negative battery cable off the terminal nut and set it aside. Wrap the end in painters tape if you fear the cable may accidentally become reconnected while you are working.
Press inward on the side tabs of the headlight wiring harness on the rear of the headlight assembly. Pull the wiring harness off the rear of the headlight assembly.
Useing your wire cutters, cut the wiring harness off the two wires to which it is attached.
Strip one inch of insulation from the end of the two wires that you cut the wiring harness from.
Slide the solder sleeve connector over each wire from Step 5.
Strip one inch of insulation off the two wires from your replacement wiring harness.
Braid the positive lead of the replacement wiring harness wire with the lead from the positive wire of the pair of wires in Step 5. Braid the neutral lead of the replacement wiring harness wire with the lead from the neutral wire of the pair of wires in Step 5.
Slide the solder sleeve connector over the braided bare positive leads. Heat the connection with the heat gun to melt the solder in the solder sleeve connector and seal the connection. Repeat this process for the neutral wire.