LED Turn Signals (99-00 Civic)
 

Most of this is copied and pasted from another of my threads. I did this on a 2000 LX 4 door. I did not research what is different on a 96-98. If you do this on your own car, PM me and let me know so I can expand this content.

Cliffs notes: I wanted to convert all of my exterior lights to LEDs without making custom boards and doing a lot of soldering. I wanted that modern flasher look because it's cool. I ended up only doing turn signals using bulbs and a flasher relay from www.superbrightleds.com.

What you'll need:
-Parking lights/front turn signals - 2x 1157A ("dual filament", "A" for Amber color)
-Rear turn signal - 2x 7440 ("single filament" for outer tail sections, 7440A for me because my tails are red/clear)
-LED bulb Flasher Unit CF13JL-02
-pliers
-screwdriver

Estimated Time:
60 minutes depending on weather, skill, and how tough your inner fender liners decide to be.

Cautions:
These bulbs are not cheap. Also, they may not be street legal depending on your local laws. I did 90% of my driving at night so I was good.

Step 1: Preparing your fuse box.
Pull your old flasher relay out. You'll be left with an obvious socket with plastic walls. The new LED flasher relay is too big to fit in the socket as long as it has those plastic walls so you have to remove them. Take some pliers, grab parts of the wall, and twist. (It's harmless, won't harm anything even if you want to reverse the conversion. The plastic just makes sure the relay never falls out.) Once the whole square of plastic is gone, the new flasher can be plugged in. (I will try to add a picture for this at a later date.)

Step 2: Replace your rear flashers.
This is a pretty easy step. Pop open your trunk, pull aside the carpet on the sides of the trunk, grab the turn signal socket (it'll be the top one), twist and pull. The bulb comes right out. Just pull. Replace with the 7440 (or 7440A) LED bulbs. Reinstall and put your carpet back in place.

Step 3: Replace your front flashers.
This one is a little harder. You can't reach the turn signals from the engine bay. Unless you already have the front bumper taken off and wish to remove the headlights themselves, the only way to swap these out is to pull a couple of the clips from the fender liner out and reach behind the fender to get to the socket. Grab the socket, twist, and pull. Comes right out. The 1157A bulbs have a different kind of socket. You can't just pull. They have to twist out. Take note of the base. One of the little tabs is lower than the other. The new LED bulb must be put in the same way or it won't work. (Be careful with these bulbs. I broke one of the little tabs off and ruined a bulb.) Remove the old bulbs, install the 1157A LED bulbs, but leave them hanging out for now. Before you put everything back together on the front end, turn your hazard lights on and make sure everything is working correctly. Once you've verified this, put the front bulbs back into their sockets, twist, and put your fender liners back on.

Boom. Done. Enjoy.