When cold on trying to start in park or neutral nothing happens,i have to wiggle the gear selector several times between 'R' an 'P' until it turns the engine over

 

When cold on trying to start in park or neutral nothing happens,i have to wiggle the gear selector several times between 'R' an 'P' until it turns the engine over. 1998 ls 400

 

That must be caused by the neutral start switch 8454030270 attached to the AT unit, I bet.

It detects the shift positions. As the car ages, it begins to show intermittent no connection problems. The most common and simple one is the no indication of the shift position at the cluster. The most serious one is the no start of the engine probably as you are experiencing now.

Once the problem begins and the adjustment is not effective, dealers usually replace the whole neutral start switch and ask you to pay more than $300. As I check the part price at Sewell , it is priced $254.41 today.

I had the exact problem 4 months ago and I decided to fix it myself. My method was somewhat strange for mechanics and it was electrically technical method and it has been quite OK since I've done. I am sure it will be OK a few to several more years from now on. It did not require me any money but also I didn't need to remove the switch nor to open inside. If you are interested in my method, I will show you more after I write the detail with drawings and photos.

 

NSS isn't exactly a common failure, though it does wear over time as it involves mechanical components.

If you aren't inclined towards buying a new one I'm sure you could get a used one for not a large sum of money from a wrecking yard.

 

It is a very common failure here in Japan. May be the high humidity and summer heat is the reason but to endure them, Toyota should had designed the switch more carefully to last longer since the contacts were all copper like this below.


The current going through the contact is very small. With that design, it is natural to have some resistance problem as is written at the page 6 of
here,
[These contacts, like the make-break contacts, in (1) may be carrying high currents at high voltages (e.g. high voltage isolators or high voltage or medium voltage fuse contacts), or carry very small currents at very low voltages (e.g. edge connectors carrying only command signals). They have to carry current reliably for long periods, without overheating or loss of contact, but do not make or break current. These contacts are not subjected to the duress of arcing, hence do not get the inherent cleaning action associated with it. They are frequently designed to have some frictional action on closing to remove superficial oxide or corrosion films which might impede contact, and copper and its alloys are the most frequently used materials for the bulk of demountable contacts.]

Then how should we deal with it without replacing the switch? There is a very simple and easy way to fix the contact. May be those who are familiar to electrical contacts can guess the idea reading above.