So a little history first, this is my son'* car, it'* a 2000 Park Avenue 3800 supercharged. This car was originally having issues going into park and if you put it down into 3rd it would get stuck and you would have to get underneath the car and force it back to park because the shifter wouldn't move at least that'* how he explained it to me. I told him it sounded like the transmission range selector that the shift cable hooks to. He had a friend mess with it and get it to where it would go into park and he just didn't shift into the manual gears below D anymore and it was ok for a but then all of a sudden it stayed in 1st gear and is stuck in limp mode. He said the shifter still didn't feel right going into D so i'm wondering if that range selector switch can cause it to go into limp mode? It does have a code for a speed sensor which i'm sure can cause it. The transmission that is in it is from a 2003 Regal 3.8 SC. 1st question is where is the range switch located? I have always seen them bolted to the tranny but a local repair shop told him it was inside the transmission and the whole K frame had to come off then the transmission pan etc. Sounds like maybe they were just trying to rip him off? Before I go there to look at it I wanted to get more info. Also is the speed sensor located near the front wheel hub like an abs sensor would be? Any advice would be appreciated so I can be more prepared when I over there to help him with it.

thanks in advance

Do you have the vehicle? If this job is being done with you as a middle man it gets way messed up. I will just give you the manual and wish you luck.

https://charm.li/Buick/2000/Park%20A...0SC%20VIN%201/

I will be fixing it but he doesn't live close to me so i'm trying to get my ducks in a row before I go there. Thanks for the reply and the manual. I appreciate it

What codes does he have? Really need to scan the network (all modules).

He said the only code present is for the speed sensor bur he didn't remember the exact code so I could know if it'* input or output speed sensor

Yeah, it is inside the transaxle. This thread kind of shows what you are talking about: https://www.gmforum.com/4t65e-hd-147...ission-297189/

Seeing that it is a used-swap from another car tells me that maybe there are inherited issues or maybe installation issues that might have contributed.

HOw exactly did you get a 2003 Regal 4t65eHD into the 2000 Park Avenue? Electronically, there are differences. Only 99-02 are the same years of compatibility
Also, the 1999-2000 Park Avenues had a TSB for a new Shift cable because the OEM one was too stiff and caused high amount of force to shift, leading to complaints.

The range switch, which is internal to the transmission ,can be replaced with an external one assuming you are willing to repin the connector harness to the transmission, and this is best done with a donor car so you can use the plugs/wire ends off a harness then run the new wires to the PCM by splicing the harness on the right wires.