Here is the link for installation instruction but i am stuck on step 4, i located the "existing harness" but unable to to know which wire is ground, tail light, or break light.

Link: Install Honda FIT LED Rear Pillar Light Tail Light JDM

 

Quoted from step 4: "black to ground, red to tail light, white to brake light"

What's there you don't understand?
The wires are not colored?

 

The colors may be off, but from the LED cluster I see three wires, blue, black and brown. In the harness I see gray, blue, brown, and black wires.

The text does not reference whether it is talking about the harness or the taillight wires.

Also, if it is a brake light, why have a connection to the tails? It should just be brake and ground. It would be cool if it were dual-function, but I don't think that is so.

Once you get them working I'd be interested to know if their intensity is well-matched to the existing lights. In the pictures the new LEDs seem a bit dim by comparison.

 

They are dual function.

I have these lights and have had them for about 2-3 weeks. They look great. They almost perfectly match the intensity of the stock tail lights.

I decided not to hook up the brake function because I just wanted them more for look rather than functionality.

They are very easy to install. Only took me about 45 mins.

Here are some videos of mine:

 

Please Explain upper tail light fitting instructions...thanks