When i turn on my headlights my lexus ls400 will not shift out of 1st gear.

It's possible u have a Major/Miner Electrical short.

If you can't find your answer to the 1994 LS400 I have owned the Lexus LS400 that car in Japan is also known as a Toyota celsior so if you were to look up information regarding the Toyota celsior the year of 1994 you can find a column gear answer to your question

Now, I'm not saying this is a fact, but my TH700R4 trans did that very thing, wouldn't come out of third. And with no 3rd it won't go to overdrive. I rebuilt the trans and found the overdrive drum was all scarred and caused the limp home thing to happen, third gear was as high as it would go. I suggest you have the trans checked out by a professional trans shop. As for it being a bear to start, that's a faulty temperature sensor. If it's not functioning, the computer doesn't know to put it into cold start mode, which increases the throttle speed and puts more fuel in the engine for starting when cold. Like a automatic choke system in earlier vehicles.

you need 1 and 2 shift solenoid and the overdrive shift solenoid

Get under the dash and watch what moves wne you put it in gear

Sounds like you replaced a lot of expensive parts when it was probably the shifter switch or a problem with the wiring between the computer and the switch or the computer to the transmission. You'll have to chase it all out, starting with being sure that there are proper signals at the computer- coming AND going.

check the main earth or negative ground between the engine in the chassi..hope it work

sounds like you have bent something underneath or broke a support bracket

slide the lower part of shifter handle down and you will find two screws, but there is 2 wires coming in from center console for overdrive button.you have to remove the center console cover and remove the 2 wires from connector and then pull up threw handle.when you go back together you will have to guide them back threw the handle.