02 3.0d vouge goes forward when in park, reverse and neutral can anyone help me?

Hi and thanks for taking time to read my post. I have an 02 vogue 3.0d. The engine runs fine forward although it is stuck in 1stt gear.
It goes forward in drive, reverse and neutral and I cannot go backwards as all gear selections go forward. When you select reverse the reverse lights come on and the parking sensors come on and there is no warning lights on the dash. It will select low gear when in neutral and when in triptronic shift it still sticks in what feels like 1st. When in triptronic the gear indicator on the dash goes into 2nd when triptronic is selected then up to 3rd but when shifting down it goes from 3 to 2 to 1. his makes no dInference as the car won't change gear. It will go into neutral when the engine he is off however. I would appreciate any help on here as I now nothing about gearboxes but I was told it could be a solonoid switch? I'm sure you guys know a lot more than me, thanks for your help.

I would think it is either the gearbox XYZ switch or the cable connecting to it - the XYZ switch on the GM box is mounted internally just above the sump and is connected to the gear selector via a lever on the outside of the box and a cable up to the gear selector.

The purpose of the switch is to tell the gear box ECU which selection you have made and to run the gearbox accordingly - if the XYZ switch is fecked, it could be giving odd signals to the ECU causing the wrong gear selctions to be made.

The XYZ switch is actuated by a cable to the gear selector in the cabin, if this cable is maladjusted, you could also get wrong selections being made as the XYZ switch is not being moved correctly....

As a final check, you could also check the multiplug of wiring that goes into the box for any signs of corrosion, loose connection of chaffed/broken wires.