The negative wire connecting the engine to the car body is corroded an

@ahmedjogmany this "shift the transmission from park (P) to neutral (N) for the engine to start." will not be related to the corroded ground strap. That, is most likely related to the neutral safety switch (or inhibitor switch). Should be located on top of the automatic transmission case, directly beneath the air cleaner assembly and battery tray.

Now, for your corroded ground strap. Depending on where and how bad it is rusted, Remove the bolt that connects it to the body. You may have to drill that out if it is to corroded. Use a wire brush and remove the corrosion on the body. Install a new ground strap and after that you can either paint over it to prevent future corrosion or apply some dielectric grease. Pictures are always good to explain things better. If anything is unclear etc. post some good pictures of what you have going on there with your question. That way we can see what you see. Voeg afbeeldingen toe aan een bestaande vraag