IDRATZ! would have had so much fun with this.. But your not too new. Hello! Welcome to the Forum.
First things first.
We got your model year and truck brand and make. So that's good. But I don't know what MMT is?
The closest I can find is this:
This:
I don't know what you are installing, so I can't trackback the wire diagram to help.
My stereo wire adapter harness has a wire for illumination and there is no place for this on mmt stereo
It may be CAN-BUS so not needed. But on a 2000? Nope. You don't have CAN-BUS in your truck.
Can you Please post Photos of what wire your working with as well as your radio and Model number, and we can help track down the issues.
Again, there are going to be a LOT of wires you may not need at all. But Again, I can't tell you for sure.
If your having issues with the install, I'm betting its off Brand Head unit. But again? Shots in the dark.
Here is your Wire pinout for 2000
Thank you to the 12VOLT!
(Credit:
Arron Miller)
Pro Street has done a few installs and they used some aftermarket
audio, and it seems that your wire diagram is the same from 1999-2006 on most Trucks. They go into some of the cavets of the install on some models. And have detailed install guides.
Easily complete your GMC Sierra stereo install by using this Sierra Stereo Wiring guide that shows you what wire does what and which speaker wire goes where
my.prostreetonline.com
Maybe this may help.
Let us know, and we can try to tackle the issue. But Like I said. I'm shooting in the dark.