Orbitautos

I had failing back lighting, so like any person who does not want to spend too much, I tried to fix it myself. First, I took it out of the car thinking it was going to be bulbs, which turned out to be LEDs. Then I tried ordering a used one and replace mine with one that had working LEDs but quickly found out that the car won't start if you replaced the speedometer and that some coding is required, which I cannot do. Next, I had two speedometers no solution, so I tried transferring the LEDs from one to another, it was very difficult but I succeeded in the end and all the failed LEDs were replaced. I put everything back in place and saw that I all LEDs were working. But then another problem popped up as new warning lights turned on that were not on previously that indicate problems with steering and brakes, which I know to not be the case. I drove the car to see if there was anything but the car drove just fine. I tried erasing the codes with an OBD but they do not get erased. So now, I am out of ideas. I am thinking of buying another used speedometer and finding out how to set it up in the car but I am not sure about coding is done. Does anyone have any ideas about how to get rid of these error lights that have turned on? Or about who does the coding for the replacement speedometer? Sorry this post was so long and thanks in advance!