Wont go in low ratio?????help????

Has any one got any ideas ive got a p38rr dse auto and when i put the gear stick in to the other side gate (low ratio) it doesnt change i can still drive it at normal speed, nothing comes up on the display,no beep,any ideas
Ive changed ;gear selector,
; transferbox and electric motor,
;checked the connections,
;losing my mind............

Low range Ecu ?

transfer box ecu looking likely :scratching_chin: where abouts in the country are you. as i have a spare ecu you could try.

thanx for replying im in stoke on trent