This is the way it went down at my house.
What you need:
1. two wiring harnesses, from whatever company, but make sure they are for the 9004 bulb. The kind I bought I believe were Nokya but I'll double check and change the brand if its wrong.
2. also you need to go to radioshack and buy some heat shrink wire insulator.
3. A lighter of some sort
4. A pair of scissors. WHEN EVER THE WORD SCISSORS IS SAID WIRE CUTTERS WOULD BE BETTER.
MAKE SURE THE WIRES MATCH THE RIGHT COLOR OF THE STOCK WIRES!
How you do it.
1. First take out the bulb and take the stock harness off.
2. Take the aftermarket harnesses and then strip them to where 1/2 inch of copper wire is showing.
Note: Do this for each of them.
3. Take a pair of scissors and cut the wires running from the stock harness about 3 inches from the inlet of the wires into the harness. The wires run into the harness, cut them 3 inches befoer they do in other words.
4. Strip another 1/2 inch of wire from the wires you just cut.
5. Take the heat shrink insulator and cut two large diameter pieces into three equal halfs each.
6. Take one of the 6 segments you should have and put one on each wire running from the new harness. Slide each so the copper is still exposed.
7. Take the exposed copper wiring and twist them together.
8. Slide the heat shrink over the bare wire and with a lighter proceed to melt the ends and shrink to where the wires will not come off.
9. When all wires have been shrunk, take the new harnesses and connect them to the bulb and place the bulb back on the headlight housing.
Note: To be safe disconnect the battery!
Here is what the final product should look like (below)
2. Light Housing
3. Passenger side wiring
4. Passenger Light Housing
Hope they all show!