Hello, I have an electrical problem that I would like to get worked out. I purchased a 2000 Blazer from an ad in our local Bulletin Board. It starts, runs, and looks great. The engine is quiet and it shifts smooth in Drive. Where the issue arises is when you shift manually into 3rd. If the vehicle is running, it produces a loud and shrill screech. If you skip 3rd and go to 2nd or 1st it makes a chirp as you skip 3rd, but shifts fine into 2nd or 1st. My dad, being the genius that he is, got the bright idea to turn the vehicle off, move the ignition switch to the ON position, and shift into 3rd. Sure enough, the vehicle attempted to start. So, my question is, what wiring could be crossed or messed up that would cause this? I'll list a few things to note next from things we figured out.

-The engine was rebuilt last summer by a "backyard mechanic that was a friend of the womans ex boyfriend"

-The vehicle does not start this way, the starter fires and the engine rolls, but it doesn't fire and start.

-I'm pretty sure that "3rd gear start" wasn't an available option in 2000, or ever.

-I plan to start in the steering column at work Tuesday since both ignition and transmission select are there.

Thanks in advance for any assistance into this matter, if you need me to try anything in particular, let me know!