Cruise Control lamp blinking
 

I've Nissan Altima 2008, I've changed the gearbox & after that, cruise control work fine till speed before 100 KM/H, however once I hit 100 KM/H it starts blinking & keeps blinking till I switch off the car & switch it on again.

The same scenario is happening, once I reach 100 KM/H it "Set" lamp keeps blinking, even if I went below 100 KM/H & it will not stop blinking till engine switched off then switched on again.

On the OBD, it shows code error "P1574 ASCD VHL SPD SEN"

Sometime, I feel like shifting is not totally good, sometime the car is under shifting & other times it's over shifting & sometime the car is Ideal.

Can anyone help.