Code P0500, reverse not engaging, but high rev?

Not really, the codes are to do with the VSS and traction control. When in reverse do the reverse light come on? If not, you could have a transmission gear range sensor that is out here is the location so you can check it out. Check out the images (below). Please let us know what happens.

Hi Ken, is the switch range gear sensor found in the gear box, or is it out on the gear box? When I looked at the diagram you sent it tell it’s something I have to check inside the gear box.

The Lexus drives very well ahead all the from gears changes very well, except reverse only revs but sometimes very little movement sometimes at all not.

I could be the reverse clutches are burned up, how does the fluid smell and have you checked the fluid level?

If so, can the reverse clutch be replaced? If need transmission replacement?

For the fluid I have not checked because we have replaced fluid twice.

It could be the only thing you might try is to install a rebuilt valve body. here is how in the images below, also you didn't say if the fluid smells burnt. When you replace the valve body new shift solenoids will be replaced as well. Check out the images (below). Please let us know what happens.

Thank you, Ken. Image is not very clear.

Did you click to enlarge the image?

Yes I did.

You need to remove the transmission pan and filter to get to the valve body. Check out the images (below). Please let us know what happens.