4 lo works 4 Hi does not

[Dominiiic]

So Idk if this is in the right forum if not please move! Well I just bought a 2003 silverado with 216000 Km with a new tranny. I absolutely love it! Although I live in canada so the winters can be rough, It's a manual floor shift and my 4 low works fine but if I try to go into 4hi any time ( moving, stopped, in neutral ) nothin works, no 4x4 light or a sound like it's even trying to shift and it is pretty annoying having to go to neutral to use 4 low to get up a slight icy hill just to switch back to 2.