I have a '07 Sonata and it was giving me issues with not allowing me to start in P from time to time.

I replaced the Neutral safety switch with a new one (Beck/Arnley) and adjusted the switch for N with the car in Neutral. Problem is it won't go in or register when in either P or D properly. I would have to forcefully or slam it into P or D to get in into gear.

If I adjust it for P then it won't go into D and vice versa. I am either adjusting the switch wrong or I got a faulty switch where the tolerance of the contacts are too far apart.

I adjusted this many times to the point where I found a compromise where it would go in P or D with a little persuasion of force. But now the weather is getting cold new freezing at nights here in Ontario, Canada. This morning I could not get it into D at all no matter how hard I slam it into gear.

Am I adjusting this wrong? I think I may just go back to the old switch, because it was only not allowing the car to start in P from time to time. But I could always throw it in N and start and still put it in D and go.

 

It does sound like you received either the incorrect switch or a defective one. That is why we always suggest to use OEM parts when available. They may cost a little more, but the probility of getting the wrong part is greatly reduced.Let us know how you make out with this OK, thanks.

 

On my Saturn, the aftermarket switch was loose on the shaft, making adjustment impossible, I had to shim it to make it work.

 

So I try to reinstall the old switch today. Set the car in N. Adjusted the Switch for N using a punch to line up the alignment holes.

Even installed the mounting bolts into the old switch by using the old marks that was left there from before. Still either acts up in P or D. So now the old switch is acting like the new one.

Leads me to believe it not the switches, maybe the shift cable or mechanism connecting the shifter?

 

What you may need to do,
Get a second person to place the shift selector in the various positions and verify if there is nothing loose between the selector in the vehicle and the arm on the trans.
You need to confirm/verify the linkage is moving to the positions selected by the lever in the vehicle. Once that is confirmed to be OK, you might place the lever on the trans in the park position then set the switch to the end position where it should be when in PARK, secure it there , then check if the vehicle will start in either park or neutral. If the trans is in the correct position internally for PARK , and the switch is at the extreme end for PARK position , the vehicle should attempt to start when turned to start position.

If not, there is a problem with either the switches or the power to and from the switches.
A little side note, make sure the shift indicator is not moving around providing incorrect info when it is not indicating the correct position.

Also, make sure the cable if used, is anchored securley , because if it is not and the cable casing is allowed to move, it will never place the inside cable to the selected position.