Years ago I got one of those Fit LED third lamp things, it's just a PCB with LEDs stuck in it and it connects via the bulb connector in the jankiest way. Twice now I've noticed in the reflection of the car, the lamp isn't lighting - but sometimes it does? Well, I need a brake lamp that will always work. I don't know what I did with the red plastic bit that goes in there - does anyone have one laying around? Thanks.

 

I would just check the connections that plugs into the socket. The little metal "legs" may need to be bent outward a little bit to make a better contact.

If you still want to go back to OEM, just pickup a red bulb..

or... 07 08 Honda Fit High Mounted Third Brake Lamp Light | eBay

or... 40 LED Third Brake Light Rear Tail Center High Mount Stop Lamp for Car Auto SUV | eBay

 

buy a DaiLed LED 3rd brake light. Don't go back to stock...